Congrats on finishing the game!
The character animations are nice.
Programming rhythm games is very hard, especially with browser builds (as different browsers on different devices with different sound interfaces could have different input and audio latency). Although even on Windows build the first ~6 notes and some notes in the middle are placed perfectly on the beat, but all others felt very random.
It would be great to see and/or hear some feedback when you miss or hit.
Keep it up!