BuddyPress.org

Welp, too late for the OP but in case anyone else gets this error when trying to get the BP Compatibility Pack working, here’s what fixed it for me.
1. Multisite enabled on your WP installation. You need to add a line to your wpconfig.php file to do so (unless there’s an admin menu I’ve missed). Here’s the directions: https://codex.wordpress.org/Create_A_Network.
2. Buddypress installed and activated. However, if you’re using the BP Compatibility Pack, it’s because you want to use your WP theme, so do not enable the Buddysite-specific theme.
3. BP Compatibility Pack installed and enabled, then you can do the walkthrough to set up BPCP and you won’t get the error.