Yesterday I couldn't figure out how to get it to work, or even what was supposed to happen, but today I hooked up my controller, restarted the browser (learned that's necessary yesterday), opened settings which by default was set to "Input: Blank" and "Output: MPKMINI2", switched it to "Input: MPKMINI2" and "Output: BUILTIN AUDIO" and I can now play along with the notes step by step. It's really fun actually :)