bbPress.org

Do not upload to bb-templates of bb-plugins. Make two new folders, if they’re not already there, called my-templates and my-plugins, and put your unzipped templates and plugins in those folders. There is no upload in the admin for themes or plugins, like there is with WordPress.

bbPress for a while was coming with those two folders, empty, but with the wrong permissions. Follow the link from ashfame to see how to fix the permissions issue.