As suggested, I have an install of Ubuntu 16.04 (virtual machine, but it's powerful enough here) with all updates and the proper g++, along with cmake and all the rest, and I have this error immediately when doing "make":

roracle@VBox:~/Downloads/ZeldaClassic-2.53/build$ make
Scanning dependencies of target zcsound
[ 1%] Building CXX object CMakeFiles/zcsound.dir/src/zcmusic.cpp.o
In file included from /home/roracle/Downloads/ZeldaClassic-2.53/./allegro/include/allegro/internal/alconfig.h:62:0,
from /home/roracle/Downloads/ZeldaClassic-2.53/./allegro/include/allegro/base.h:41,
from /home/roracle/Downloads/ZeldaClassic-2.53/./allegro/include/allegro.h:25,
from /home/roracle/Downloads/ZeldaClassic-2.53/src/zc_alleg.h:16,
from /home/roracle/Downloads/ZeldaClassic-2.53/src/zcmusic.cpp:13:
/home/roracle/Downloads/ZeldaClassic-2.53/./allegro/include/allegro/platform/alucfg.h:37:39: fatal error: allegro/platform/alunixac.h: No such file or directory
compilation terminated.
CMakeFiles/zcsound.dir/build.make:62: recipe for target 'CMakeFiles/zcsound.dir/src/zcmusic.cpp.o' failed
make[2]: *** [CMakeFiles/zcsound.dir/src/zcmusic.cpp.o] Error 1
CMakeFiles/Makefile2:67: recipe for target 'CMakeFiles/zcsound.dir/all' failed
make[1]: *** [CMakeFiles/zcsound.dir/all] Error 2
Makefile:83: recipe for target 'all' failed
make: *** [all] Error 2
There is literally no "platform" directory in the "allegro" directory file, so there's no way it could find "alucfg.h" no matter how hard it tries. I don't know if this was intended, as the GitHub page suggests all changes made to allegro are in the file, or in "all422-fixed.zip" which also does not exist, as the GitHub readme points to a .allegro file directory which also does not exist in the downloaded package.

Any help would be nice here. (I'm baffled as to why people don't build in Linux first as a rule anyway. I figured a free platform with everything you need would be attractive to developers.)