if the integration is working fine it's just matter of permissions.
with 5.x and 6.x it's not as simple as just having them go to ccmuser, you need to assign make them part of a group which has access to the ccmuser
think of it as MLA extended, not only for the admin users who access CCMAdmin but also for end users who try to get access into CCMUser
the ccmadministrator has a role as able to log into CCMAdministration
you need to assign the end users permission to log into the CCMUSer
if this helps, please rate