In the Dragon Quest Stage 3 (install Confluence), there appears to be a couple of steps missing

[wildcard]

If you don't create the groups "confluence-administrators" and "confluence-users" in the jira instance before establishing jira as the user manager and having confluence authenticate through jira, you get a "Not Permitted" error. Uncertain if establishing the groups AFTER hooking confluence up to jira fixes things, but I do know that if you create the groups before hand (and assign users to those groups), it will work.

[Rafi Sabel]

Confirmed - this works, but only if you create these groups in JIRA before performing the Confluence setup.