That's strange, the game won't open from the itch app on my mac either. If you instead click "show in finder", you might be able to run the executable directly. Either that, or play on browser or try downloading the mac build directly from the downloads section of the game page (not itch app)
Alright so it turns out it's because I'm zipping up a .dmg file, which is already an archive file. I'll upload the updated file in 2 weeks once the voting period for this jam ends. link to discussion