I had been stymied by engine errors (as in, the engine would not start, throw an exception, or give me the time of day) with SpringLobby running a normal ZK game.
Turns out that it was because I had to set the default engine to 94.1 just to be able to log in on SpringLobby.
Now, I set the default engine to 94.1 before I log in, and set it to 91.0 or 91 (both have folders. Why is this? I do not know) after I have logged in.