Hey, I'm trying to play multiplayer games again after a few years of inactivity. When I try to join a game it only says, "not connected".

what version are you using?

Make sure you're connecting to the right servers according to your belt. Start with beginner, and work your way up. If you know you have blue belt, for example, go to semipro.

I downloaded the newest version off the Toribash homepage. So 3.91, I believe.

Check this thread to determine the problem for your issues.
Is your firewall possibly blocking proper connection to multiplayer?

I turned off my firewall completely and the problem is still persisting. Maybe I'm doomed to free play.