The part where the music changes there should be 3 platforms that pop up like steps right after you spawn in. The game saves your state, so if you reload the page you can continue from level 5. Let me know if that fixes things for you!
I changed the refresh rate to 60 now I am stuck here18 days ago(+1)
The timing is pretty tight.. I've always had a hard time tuning difficulty for jam games! Something that might help is you can use the moving platforms at the start to get a jump boost if you time it right, and get a little ahead of the track.