Re: Problem Installing buddypress…
Rename the buddypress folder in wp-plugins via FTP or cPanel to deactivate BuddyPress.
The correct translation in WP lingo is “You do not have sufficient permissions to access this page.” And while this was triggered by activating BuddyPress, it starts with your WordPress installation.
There are plenty of threads in WP.org forums and Google search with different solutions to get back your Admin/Super Admin privilege in the installation. Good luck.