The map is based on Fed X Gaming's Minecraft tutorials, with some edits for 1.17. There is FNaF fan games but that's something you need to unlock, it does involve the sign at the desk. Here is the location if you don't want to look.
It is in Ultimate Custom Night, in the left hall there is a two high painting, go inside and click the button.
This was a map for my friend as well so if you find anything without context it was because my friend would understand it.