Link Page to Groups is a small plugin for BuddyPress that allows site admins to link regular WordPress pages to individual BuddyPress groups. You might use this plugin to associate a group with page providing some instructions or whatever you want.
Dashboard Edit Group Page:-
Single Group Screen:-
If you have enabled it for front end (Please take a look at this post for the details ), Then the Group admin can also choose the page to attach from Group->manage->settings screen. Here is a screenshot.