with BP 161 if you click on the ‘setting’ link on the plugin page you get the permission error. You first have to click on the ‘Dashboard’ tab and you will see a ‘BuddyPress Setup’ link that does the initial setup, then you can use the setup button on the plugin page.
Having that ‘initial’ setup link in under the Dashboard’ tab is a bad idea espically since it goes away after you first use it.
After you activate the plugin, check under ‘Dashboard’ for a ‘BuddyPress’ setup tab. Untill I did that I was getting the ‘Insufficent permission…’ message