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)

worked， ty

thank u for the map :3 me and my sisters finally got it (local coop xd) +1

im looking for two players... (thanks for the map!)

thankyou for the map but it needs three people and none of my mates have the game

very fast and easy way to complete achiev.