I believe this is now fixed. Would you mind giving it another try and letting me know how it goes? Thanks!
that issue was fixed, but different issue seems to be occurring!
I'm sorry, but an uncaught exception occurred.
While loading <'Image' u'00-renpythm/images\\up.png'>:
File "game/script.rpy", line 52, in script
call screen rhythm_game(audio_path, beatmap_path, beatmap_stride=2)
File "renpy/common/000statements.rpy", line 570, in execute_call_screen
store._return = renpy.call_screen(name, *args, **kwargs)
File "game/00-renpythm/rhythm_game_displayable.rpy", line 207, in render
render.place(note_drawable, x=note_xoffset, y=y_offset)
Exception: Backslash in filename, use '/' instead: u'00-renpythm/images\\up.png'
also copy-pasting my comment from above: i noticed that the download comes with copyrighted music - i suggest switching to music you have permission to use! (as it is now i don't feel comfortable recommending this engine to other people since it seems to just have music downloaded from youtube included in the files.)