I downloaded the pc version of Steam using playonmac. When I try to enter my safehouse the game crashes. It also often crashes when I go into a lobby. I did manage to get into one game but it was so laggy it wasn't worth playing. Here is my Mac info:
-iMac 21.5 inch, mid 2011
-Mac OSX Lion version 10.7.5
-Memory: 4 GB 1333 MHz DDR 3
-Graphics: AMD Radeon HD 6750m 512MB
Here is the debug report from steam startup to crash (this crash happened when I tried to enter safe house).