Can you trying logging in with a user that had administrator access on the Forums / KB instance?
Yes. I used admin to log in to my Forum/KB, and I have full priv to manage documents. Using the same user admin to log in to my new clearspacex instance, I was not able to modify user accounts. I do not see "Systems" tab. I cannot change system properties.
The imported group 'admin' group has group id of 1006 now. I think at the Forum/KB, it was single digit.
Take a look at this article - http://www.jivesoftware.com/jive/entry!default.jspa?categoryID=2&externalID=281&fromSearchPage=true
There is a section about permissions and resetting them appropriately for admin users.