LaTeX error report unusual subfigure method from stackexchange

Compile Error. Sorry, your LaTeX code couldn't compile for some reason. Please check the errors below for details, or view the raw log.
 main.tex, line 349
Package pdftex.def Error: File `Figures/MedianGroups.png' not found: using draft setting.

The compiler cannot find the file you want to include. Make sure that you have uploaded the file and specified the file location correctly.

 Learn more
See the pdftex.def package documentation for explanation.
Type  H <return>  for immediate help.
 ...

l.349 ...=0.5\textwidth]{Figures/MedianGroups.png}

Try typing  <return>  to proceed.
If that doesn't work, type  X <return>  to quit.

 main.tex, line 356
Missing number, treated as zero.

<to be read again>
                   \unhbox
l.356 ....2\textwidth]{Figures/MedianGroups1.png}}

A number should have been here; I inserted `0'.
(If you can't figure out why I needed to see a number,
look up `weird error' in the index to The TeXbook.)

 main.tex, line 356
Illegal unit of measure (pt inserted).

<to be read again>
                   \unhbox
l.356 ....2\textwidth]{Figures/MedianGroups1.png}}

Dimensions can be in units of em, ex, in, pt, pc,
cm, mm, dd, cc, nd, nc, bp, or sp; but yours is a new one!
I'll assume that you meant to say pt, for printer's points.
To recover gracefully from this error, it's best to
delete the erroneous units; e.g., type `2' to delete
two letters. (See Chapter 27 of The TeXbook.)

 main.tex, line 357
Missing number, treated as zero.

<to be read again>
                   \unhbox
l.357 ....2\textwidth]{Figures/MedianGroups2.png}}

A number should have been here; I inserted `0'.
(If you can't figure out why I needed to see a number,
look up `weird error' in the index to The TeXbook.)

 main.tex, line 357
Illegal unit of measure (pt inserted).

<to be read again>
                   \unhbox
l.357 ....2\textwidth]{Figures/MedianGroups2.png}}

Dimensions can be in units of em, ex, in, pt, pc,
cm, mm, dd, cc, nd, nc, bp, or sp; but yours is a new one!
I'll assume that you meant to say pt, for printer's points.
To recover gracefully from this error, it's best to
delete the erroneous units; e.g., type `2' to delete
two letters. (See Chapter 27 of The TeXbook.)

 main.tex, line 358
Missing number, treated as zero.

<to be read again>
                   \unhbox
l.358 ....2\textwidth]{Figures/MedianGroups3.png}}

A number should have been here; I inserted `0'.
(If you can't figure out why I needed to see a number,
look up `weird error' in the index to The TeXbook.)

 main.tex, line 358
Illegal unit of measure (pt inserted).

<to be read again>
                   \unhbox
l.358 ....2\textwidth]{Figures/MedianGroups3.png}}

Dimensions can be in units of em, ex, in, pt, pc,
cm, mm, dd, cc, nd, nc, bp, or sp; but yours is a new one!
I'll assume that you meant to say pt, for printer's points.
To recover gracefully from this error, it's best to
delete the erroneous units; e.g., type `2' to delete
two letters. (See Chapter 27 of The TeXbook.)

 main.tex, line 359
Missing number, treated as zero.

<to be read again>
                   \unhbox
l.359 ....2\textwidth]{Figures/MedianGroups4.png}}

A number should have been here; I inserted `0'.
(If you can't figure out why I needed to see a number,
look up `weird error' in the index to The TeXbook.)

 main.tex, line 359
Illegal unit of measure (pt inserted).

<to be read again>
                   \unhbox
l.359 ....2\textwidth]{Figures/MedianGroups4.png}}

Dimensions can be in units of em, ex, in, pt, pc,
cm, mm, dd, cc, nd, nc, bp, or sp; but yours is a new one!
I'll assume that you meant to say pt, for printer's points.
To recover gracefully from this error, it's best to
delete the erroneous units; e.g., type `2' to delete
two letters. (See Chapter 27 of The TeXbook.)

 main.tex, line 360
Missing number, treated as zero.

<to be read again>
                   \unhbox
l.360 ....2\textwidth]{Figures/MedianGroups5.png}}

A number should have been here; I inserted `0'.
(If you can't figure out why I needed to see a number,
look up `weird error' in the index to The TeXbook.)

 main.tex, line 360
Illegal unit of measure (pt inserted).

<to be read again>
                   \unhbox
l.360 ....2\textwidth]{Figures/MedianGroups5.png}}

Dimensions can be in units of em, ex, in, pt, pc,
cm, mm, dd, cc, nd, nc, bp, or sp; but yours is a new one!
I'll assume that you meant to say pt, for printer's points.
To recover gracefully from this error, it's best to
delete the erroneous units; e.g., type `2' to delete
two letters. (See Chapter 27 of The TeXbook.)

 main.tex, line 363
Extra }, or forgotten \endgroup.

\@endfloatbox ...pagefalse \outer@nobreak \egroup
                                                  \color@endbox
l.363 \end{figure}

I've deleted a group-closing symbol because it seems to be
spurious, as in `$x}$'. But perhaps the } is legitimate and
you forgot something else, as in `\hbox{$x}'. In such cases
the way to recover is to insert both the forgotten and the
deleted material, e.g., by typing `I$}'.

 main.tex, line 363
Improper \prevdepth.

<recently read> \prevdepth

l.363 \end{figure}

You can refer to \spacefactor only in horizontal mode;
you can refer to \prevdepth only in vertical mode; and
neither of these is meaningful inside \write. So
I'm forgetting what you said and using zero instead.

 main.tex, line 363
You can't use `\prevdepth' in horizontal mode.

\end@float ...pdima \prevdepth \vbox {}\prevdepth
                                                  \@tempdima \penalty \@floa...
l.363 \end{figure}

Sorry, but I'm not programmed to handle this case;
I'll just pretend that you didn't ask for it.
If you're in the wrong mode, you might be able to
return to the right one by typing `I}' or `I$' or `I\par'.

 main.tex, line 363
Missing number, treated as zero.

<to be read again>
                   \penalty
l.363 \end{figure}

A number should have been here; I inserted `0'.
(If you can't figure out why I needed to see a number,
look up `weird error' in the index to The TeXbook.)

 main.tex, line 363
Illegal unit of measure (pt inserted).

<to be read again>
                   \penalty
l.363 \end{figure}

Dimensions can be in units of em, ex, in, pt, pc,
cm, mm, dd, cc, nd, nc, bp, or sp; but yours is a new one!
I'll assume that you meant to say pt, for printer's points.
To recover gracefully from this error, it's best to
delete the erroneous units; e.g., type `2' to delete
two letters. (See Chapter 27 of The TeXbook.)

 main.tex, line 368
LaTeX Error: Not in outer par mode.

See the LaTeX manual or LaTeX Companion for explanation.
Type  H <return>  for immediate help.
 ...

l.368 \centering

You've lost some text.  Try typing  <return>  to proceed.
If that doesn't work, type  X <return>  to quit.

 main.tex, line 389
LaTeX Error: Not in outer par mode.

See the LaTeX manual or LaTeX Companion for explanation.
Type  H <return>  for immediate help.
 ...

l.389 \centering

You've lost some text.  Try typing  <return>  to proceed.
If that doesn't work, type  X <return>  to quit.

 main.tex, line 409
LaTeX Error: Not in outer par mode.

See the LaTeX manual or LaTeX Companion for explanation.
Type  H <return>  for immediate help.
 ...

l.409 \centering

You've lost some text.  Try typing  <return>  to proceed.
If that doesn't work, type  X <return>  to quit.

 main.tex, line 429
LaTeX Error: Not in outer par mode.

See the LaTeX manual or LaTeX Companion for explanation.
Type  H <return>  for immediate help.
 ...

l.429 \centering

You've lost some text.  Try typing  <return>  to proceed.
If that doesn't work, type  X <return>  to quit.

 main.tex, line 446
LaTeX Error: Not in outer par mode.

See the LaTeX manual or LaTeX Companion for explanation.
Type  H <return>  for immediate help.
 ...

l.446 \begin{figure}[!ht]

You've lost some text.  Try typing  <return>  to proceed.
If that doesn't work, type  X <return>  to quit.

 main.tex, line 501
LaTeX Error: \begin{figure} on input line 354 ended by \end{document}.

See the LaTeX manual or LaTeX Companion for explanation.
Type  H <return>  for immediate help.
 ...

l.501 \end{document}

Your command was ignored.
Type  I <command> <return>  to replace it with another command,
or  <return>  to continue without it.

 output.aux, line 501
You can't use `\end' in internal vertical mode.

\enddocument ...es \z@ \Call@AtVeryVeryEnd \@@end

l.501 \end{document}

Sorry, but I'm not programmed to handle this case;
I'll just pretend that you didn't ask for it.
If you're in the wrong mode, you might be able to
return to the right one by typing `I}' or `I$' or `I\par'.

 output.aux, line 501
Missing } inserted.

<inserted text>
                }
l.501 \end{document}

I've inserted something that you may have forgotten.
(See the <inserted text> above.)
With luck, this will get me unwedged. But if you
really didn't forget anything, try typing `2' now; then
my insertion and my current dilemma will both disappear.

 main.tex
Emergency stop.

<*> main.tex

*** (job aborted, no legal \end found)


Here is how much of TeX's memory you used:
 38555 strings out of 492164
 760956 string characters out of 6125314
 1225634 words of memory out of 5000000
 42285 multiletter control sequences out of 15000+600000
 547615 words of font info for 81 fonts, out of 8000000 for 9000
 1141 hyphenation exceptions out of 8191
 60i,18n,67p,2113b,1760s stack positions out of 5000i,500n,10000p,200000b,80000s
!  ==> Fatal error occurred, no output PDF file produced!