Hi! I also got confused about the sans fight and it seems it is supposed to be there. I won the fight and didn't surrender as suggested by the lovely Dino and continued playing Pap's route with no issue.
The section you are supposed to wait on is the one where it tells you to drop them. Don't click on anything and if you scroll down after 16 sec you'll get the option to keep the notes. Do not throw them away!
hope this helps <3