As specified in the "Known Issues" list, the Source Control plug-ins (Perforce and Subversion) are not officially supported yet in the Wwise Authoring Application BETA for Mac.
In the meantime, if you would like to experiment with the Subversion source plug-in, make sure to install the latest "Wwise_v2013.2.8_Build_4865_MacAuthoringApplicationBETA" build.
The Subversion source plug-in has been enabled in this build, even though it's not officially supported yet.
Note:
Source control operations can also be performed within the Mac OS X environment using the Terminal or any other third-party Source Control software.