Fritzbot (RTCW) does not run on Mac servers nor Hosts. And the latest versions can not run on Mac Clients. Sorry.
This is implied in the warning on the
wiki. And if you read the
FAQ on the FritzBot ET wiki you should understand why. Should you chose to play ET you should be able to use plain vanilla ET on your Mac to connect to a windoze Fritzbot ET server or host. You won't get the FritzBot ET menus but client wise that is not critical in ET.
No to the question you will ask next. As FritzBot code remains the property of Mal, there are no plans to port the code to a Mac any time soon AFAIK.