Re: New to bbPress, Trying to use bbPress 2.0 Plug-in, having problems
That’s the risk when you run software that didn’t have a proper release yet 
Proper documentation will come in time, I have no doubt about that.
If you were running the plugin that’s in the wordpress repository at the moment (beta2b or something) you might want to change that with the one in trac (https://bbpress.trac.wordpress.org/browser/branches/plugin) that has some fixes in it.
I don’t know if they’ll fix your problem though. I never had to add any code to my functions.php to make it work and while I do have a message in my dashboard “Theme does not natively support bbPress”, it works pretty good