When someone subscribe and receive and email of confirmation. When they click on it, it create this page. "Activate your Account... Please provide a valid activation key. Activation key : ___________ Activate button.
Is it right? They don't have access to their account.
http://prntscr.com/jktudz
If yes, where do they find the key for activate the account?
As you know that this is totally buddypress module.
Please check that if there is some activation key in the link that is emailed ?
It should appear something like this :
http://your-site.com/activate/65c11d3e24b5499c46cbcd073bd13967/