BuddyPress.org

By default, BP group forums can be accessed at:
hxxp://example.com/forums/

If your external bbPress is also installed in /forums/, you’ll want to rename BP’s forums slug to something else.

You can do this by adding the following in your wp-config.php or bp-custom.php:
define( ‘BP_FORUMS_SLUG’, ‘group-forums’ );

In the example above, your BP forums can now be accessed at hxxp://example.com/group-forums/

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If you’re looking at theming your external bbPress install to match BuddyPress’ default theme, use the bbPress theme I mentioned above:
https://bbpress.org/forums/topic/buddypress-default-theme-for-bbpress-1