To switch it to use primary groups go to Admin CP -> Plugin Manager
Edit the TWO plugins Calendar Setup and Cache Header Calendar...
In BOTH find the line:
Code:
!is_member_of($vbulletin->userinfo, explode(",", $vbulletin->options['bop5hc_groups'])) AND
and change them to:
Code:
!in_array($vbulletin->userinfo['usergroupid'], explode(",", $vbulletin->options['bop5hc_groups'])) AND
Then save the plugins.