Wait is there the "assets" folder in the zip? Last time I had an error like that was because it needed the assets folder with stuffs like "player.png" inside
Basically the problem is the sprite files not being loaded D:
EDIT: I'M SUCH A IDIOTTTT!!!!! I JUST CHECKED IT AND INDEED I FORGOT TO PUT IT IN!!!
EDIT 2: I have fixed it! I have put the assets folder in the ZIP file now. Please try it again m(_ _)m