I read elsewhere that after you beat the dragon in the elevator hall that you unlock you own room or something. I beat the dragon and cleared out everything in the room but nothing is happening. I approach the elevator and it says it roars to life but does nothing else. What am I missing?

In 5.2 you need to do the same in another elevator floor, then the two will be linked

In 5.3 (work in progress version) same thing, but there is also The Summit which is a special always available room