BuddyPress.org

You mean iThemes Builder can’t load the BuddyPress template files transferred during the BP Template pack process? While iThemes hasn’t created a bridge to adapt BP to their themes, strange that they have not promoted using BP template pack instead.

As for additional styling, there’s a panel during the integration process where you have option to include the CSS provided in BP Template Pack to start you off. Then you just add/adjust styling to taste.