slide down won't work

[zoeblue111]

HELP
hi, for the Rotated Revealers website from codrops the pages will not scroll and I cannot figure out how to fix this without affecting the start page!

Here is the link to the page:
https://tympanus.net/codrops/2019/04/18/how-to-create-and-animate-rotated-overlays/

Thank you so much!