Hey hey! Unfortunately, from what I've been told over the years by other mac users, it's mainly down to the fact that mac has more enhanced security compared to windows, and so doesn't like unsigned indie games >.< Some folks have said they have the issue of not being able to open almost all mac builds of indie games on itch :(
Anyways, I made a whole post about it a while back that I keep updating with a bunch of info from different users with different things folks can try :3 But one of my friends was able to give me a really quick and easy way of fixing the not opening issue for most people!
So, she said that you just need to go to system preferences, then click on security and privacy, and then at the bottom, she said it should ask if you want to allow the app to play anyway.
If that doesn't work, this is the big ol list of other stuff I've compiled over the last couple of years xD Most of it doesn't make much sense to me, but hopefully, it does to Mac users x3