hmmm I'm not super familiar with Mac but I'm looking through some help forums and found This it may have some helpful info as I think it may be a PC issue like where you may need to reinstall it or parental controls could be affecting it
The info in your first link worked! I used The Unarchiver to open the zip, then had to move "Game.app" into a new folder, then it worked. Thanks a lot for looking into it for me. I can rarely get games in the RPGM community to work on my computer, so I'm very excited to dive into your demo.