ffmpeg build error with ffmpeg-build-script.

building ffmpeg - version 5.0.1
=======================
Downloading https://ffmpeg.org/releases/ffmpeg-5.0.1.tar.bz2 as ffmpeg-5.0.1.tar.bz2
... Done
Extracted ffmpeg-5.0.1.tar.bz2
ERROR: x265 not found using pkg-config

If you think configure made a mistake, make sure you are using the latest
version from Git.  If the latest version fails, report the problem to the
ffmpeg-user@ffmpeg.org mailing list or IRC #ffmpeg on irc.libera.chat.
Include the log file "ffbuild/config.log" produced by configure as this will help
solve the problem.
$ make -j 4
Makefile:180: /tests/Makefile: No such file or directory
make: *** No rule to make target '/tests/Makefile'.  Stop.

Failed to Execute make -j 4