Typically Mac issues (on operating system versions prior to 11 like yours) and a result of permissions issues. The two solutions that typically work are to either move the game folder into your "applications" folder and then run it, or assign read/write permissions to the game folder manually, this link should help. https://support.apple.com/en-ca/guide/mac-help/mchlp1203/mac (Be sure to change it to your OS version when you load the page.)
If this doesn't solve the problem let me know and I can see if there's anything else to try.