I got you, Adelaide Metro!
I made it into the city by myself, and am I ever chuffed about it. The driver was a bit surly when I handed him a $20 bill, but he sighed and fished a wad of bills out of his pocket to make change. (!) I took the O-Bahn. I got off at the wrong stop (Adeliaide Metro's trip planner is worse than useless). I made it to the Gardens on time.
To all of the relatives I've forced onto transit in the past few years: I'm so, so sorry. I forget how totally non-intuitive and scary buses are in an unfamiliar city. You all survived, but: yeah. This is hard stuff.