I created a new Chrome profile, installed extension, and this time it autodetected:

  [INFO] DanceJump: Tap-to-Beat enabled (fallback mode) - UI hidden until needed
  game.js:35 [INFO] DanceJump: Beat Tracker enabled - attempting audio analysis
  game.js:35 [INFO] DanceJump: Background Tracker Started successfully
  game.js:35 [INFO] DanceJump: Stage 1 - Starting auto-generation with placeholder chart

So good job! Tried it with this song:

https://www.youtube.com/watch?v=qMWqNXVCFiw

Feedback:

Default steps were pretty simple, the "arrow" on the right only lets you pause/unpause. I couldn't figure out an easy way to crank up the difficulty. You might even consider an auto-increase of difficulty. As they get more correct, increase the density of arrows as the song progresses.