Works fine, some tips for others:
1. All 3 players have to interact with the piano at the same time, you can tell when all 3 characters animations are in sync.
2. Then keep interacting and the song will automatically end around the 55 second mark.
3. You can do this with just one friend who doesn't need to own the game (1P = your keyboard, 2P = your controller, 3P = your friend via remote play)

Wait where your main map ? or you make it smaller

I need two people for this achievement. :/

Great Map for the achievement! TY, we got it!

thanks