My absolute failure at base64 decoding

str := "Hello, world!"
base64_encode(str)

base64_encode(strIn) {
    Static dwFlags := 0x1                       ; Base64 without headers

    szStrIn := StrPut(strIn)                    ; Get size of string
    bufStrIn := Buffer(szStrIn)                 ; Create a buffer for string
    StrPut(strIn, bufStrIn)                     ; put string into buffer

    ; Showing that the buffer exists along with pointer and size
    MsgBox "szStrIn: " szStrIn "`nbufStrIn.Ptr: " bufStrIn.Ptr "`nbufStrIn.Size: " bufStrIn.Size

    bufSzStrOut := Buffer(4, 0)                 ; Create buffer for return string size

    ; Fat arrow function b/c only the last 2 options are changed
    cryptBin2Str(pszString, pcchString) =>
        DllCall("crypt32\CryptBinaryToString"   ; https://learn.microsoft.com/en-us/windows/win32/api/wincrypt/nf-wincrypt-cryptbinarytostringw
            ,"Ptr"   , bufStrIn.Ptr             ; [in]            const BYTE *pbBinary,
            ,"UInt"  , bufStrIn.Size            ; [in]            DWORD      cbBinary,
            ,"UInt"  , dwFlags                  ; [in]            DWORD      dwFlags,
            ,"Ptr"   , pszString                ; [out, optional] LPWSTR     pszString,
            ,"UInt*" , pcchString)              ; [in, out]       DWORD      *pcchString

    ; Run bin2str
    ; pszString is null because I need to get return string length
    ; bufSzStrOut receives the calculated length of return string (in TCHARs)
    if !cryptBin2Str(0, bufSzStrOut.Ptr)
        MsgBox "CryptBinaryToString failed"


    ; Get return string length from buffer
    bSize := NumGet(bufSzStrOut.Ptr, 0, "Uint")

    ; I can't even get to here without screwing things up
    ; No error is thrown by the DLL call but bSize is 0
    ; I fcking quit at this. I've wasted hours so far and the only thing I've
    ; succeeded at is failing in accomplishing anything
    MsgBox(bSize)



    ; The rest of the code that I ~WOULD~ have tried if I could actually get the most basic
    ; of DllCalls to work
    ; But I can't because apparently, I ate a bunch of lead paint chips when I was younger
    ; and it has permanently damaged what little bit of smooth brain I actually have



    ; Create a buffer for the return string
    ; Set string size using bSize
    bufStrOut := Buffer(bSize)

    ; Run bin2str again
    ; Pass pointer to string buffer in as well as pointer to size of buffer
    if !cryptBin2Str(bufStrOut.Ptr, bufSzStrOut.Ptr)
        MsgBox "CryptBinaryToString failed"

    ; This should show the base64 encoded string
    MsgBox(StrGet(bufStrOut,,"UTF-8"))
    return
}