I've looked into this further, and it looks like unfortunately RPG Maker MV actually stopped working on Mac OS 10.15, not 11 like I previously thought. (There is an official post from RPG Maker that claims 11 is the cut off, but 10.15 is when Mac OS stopped supporting 32 bit programs, which is what I believe the problem is.)
You can most likely run the "Web" version of the game through your browser, though the browser version is not compatible with the plugin that makes your characters appearance change in-game, so you'll be stuck with the default appearance outside of the paperdoll. If you do want to give the web version a try you'll probably need to follow this link to set up your browser to run the game properly. https://www.reddit.com/r/RPGMaker/comments/dqvdqo/fix_error_failed_to_load_dataa...
Sorry about the inconvenience there, I had not realized there were issues with OS 10.15. I've updated the page on that now.