Ok so after doing some research it looks like there are issues that can come from trying to run a mac build of the game that was developed on windows (I use windows). It seems there's no easy way to fix this on my end unless I get a mac myself, but here is a link to the unity forums where someone describes the same issue and their fix for it. The original poster/top comment has a section at the end of their post with instructions on how to get the game to run. Please try it and let me know if it works. Sorry again about the hassle! MAC FIX INSTRUCTIONS