Sounds like a problem with the settings on your mac or the folder. You could try to start the game as an administrator (at least that how you can do it on windows), try to lower the security settings for the folder (or your system), or you could try to move the game to a different location. The game can't run on write-protected locations, for example usb-sticks.
If neither works, try to google the error message. It's not a game related issue, but something in the settings of your system.