I have seen that Klingons are unlocked at lvl 6. Does this mean Admeral or something else?
There are 45 levels in the game at the moment. so Lvl 6 is lieutenant not tier 6.
and to copy and paste the sticky
" 1: Get level 6. 2: complete fed mission "stop the signal." We will update as available. We do know that you aren't notified until you do a zone transition after unlocking it."
To get to stop the signal the fastest do the following missions in order.
Hide and Seek
Starbase 24 outside Fleet action
Starbase 24 mission
Stop the signal