I'm not super tech savvy, but with Macs there are usually a couple of possible reasons. Sometimes you need to change the permissions to open an app, it wasn't this complicated before but they changed things a couple of years ago iirc. Usually it's application permissions (usually found in privacy and security) and with an app downloaded from the internet you always need to right click and use the manual "open" option, not just double click on the app. If none of that works, there may be a problem with the app itself, but it sounds like an issue I had a couple of months ago with a different itch-downloaded game lol