You must have an active connection to Steam to continue, please check your network connection and try again

My network connection is fine. I’m signed in, and my Steam username and avatar are showing up in-game. Is this just a server overload thing?

No, Steam went down for everyone for a moment, not just BB players.

Got it, thanks. Steam opened and logged in fine for me, as well as downloading the required files properly, so I hadn’t thought it was Steam itself.