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 "" 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.)