ok,
to separate into categories use
https://wordpress.org/plugins/bbp-style-pack/
and go to
dashboard>settings>bbp style pack>forum template and select the alternate template
Then go to
Dashboard>settings>forums>forum root
and note what that is called – usually ‘forums’
then create a page called whatever the forum root says eg ‘forums’ and into the content of this put
[bbp-forum-index]
[bbp-topic-index]
That should all work, but come back if you have queries