In order to run the game on a MAC now you NEED to run it via wine or crossfire or a similar software.
There was never a real official version for mac, the one you see there is outdated now and something Razmirz made himself that other users could have, a FH game with wine packed into it giving the mac users a possibility to run the game without it.
If I were you guys I'd try to get Wine on your macs, it's free. There's tutorial vids on youtube how to use it aswell.
If the installer is corrupted it shouldn't have to do with this. Either it is that your computer can't read the installer because of it's an unknown file, or because it's broken. If it's broken, you need to claim a new one by downloading it. Broken installers are common when using a weak connection
