Hi again! Another OSX player found a solution to what we believe may be the same issue. Please could you try the top-voted solution in this thread? https://apple.stackexchange.com/a/181031
It involves using the terminal to change the app to be executable. Not sure why this is not being set by Unity when I build it but here we are.
I'm fairly certain the game was built for 64-bit OSX too, since 32-bit is deprecated in Unity nowadays.
Please let me know whether or not that works. Thanks, and sorry!