Hello, maybe something went wrong during installation. I would try to download the zip file again, and perhaps unzip it with another unpacking software (such as Keka for example).
If it still doesn't work you could try to find the output log file and check that for clues. On Mac, I think it's usually in ~/Library/Logs/Unity/Player.log
(Or, send the log to fpvfreerider@gmail.com and I will have a look at it and see if I can figure out what it might be).