Hyperion PCBS - Dimension security - not showing all users

I am attempting to apply dimension security to some members.  When I select a member and click the "Assign Access" icon I can pick users or groups.  It turns out the only users that show up are ones that are setup as SFTP users and the only groups that show up are the default roles.  I would like to create custom roles so I can use them like in Classic Planning (ex. to grant access for East Planners).  Regular users and custom groups do not show up.  Does anyone know if I have something set wrong so that regular users