MAC right? make you get either the normal or 64 depends on you computer.
Here is an guide to install for mac
Okay forget winrar then and try unarchiver. That should beable to extract rar files as well.
Here is an tut. video
How to Open Rar Files on Mac - YouTube
Make sure to redownload the mac version of the game just incase. extract the rar file and it should extract and .app file, double click it and it should start. I think, since macs make it way to confusing.