Hi there! We’ve been trying to find a good answer for you.
Apparently, it’s a known bug that sometimes Mac builds don’t open via direct downloading in the Itch browser for some people. The only tested workaround we’re aware of right now is opening the game via the Itch app, which is generally safer anyway. That should make the game work for you whenever a direct download doesn’t.
It’s a mystery, I’m sorry! 😭