hi,
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/
where value marked in dark is activation key pasting this in the textbox and submitting on activate page will also activate the account of the user .
Please also try to setting a redirect page in wp-admin -> wplms -> buddypress -> "Redirect Page on User Activation" .