So I've been stuck outside of the locked cavern door on the 3rd floor in vault 22 for quite some time now, and I can't get the damn thing open. I went to the overseers office, unlocked everything, got the cave keycard from that shelf in the room on the left, and went back to the terminal next to the cave door, thinking it would unlock.

But, no luck. I have the key, I'm right next to the door, but the terminal on the wall just won't open the door.

So what do I do (beyond using tcl in console and just slipping through the walls)?

It mean's you have to use the terminal to open the door to the cave.