(Before starting, if you find some English errors it's because I'm Italian)
When you enter the custom map make sure you have the resource pack. Read the book that will be on your right which contain the rules. They are:
- You can play with 2 or more friends.
- Don't use tricks.
- Be sure you're using the map resource pack.
To start the map you will need to click on the button in front of you where there will be a hologram with "Start Game" written on it. If you have already played the map and want to replay it, just press the "Reset" button.
That's all. I hope you will be frightened! :)
Note: By now almost everyone has seen that there was a piece of the map that was a bug. That is the one where you return to the starting point and you can no longer go out. I solved it, sorry for the mistake.