After that William led all of them towards the portal area. He instructed them if they got separated, they had to keep walking in the opposite direction of where the gravity came from.
As he doubted, the grand army got separated into many areas. But thanks to his arrangement, they all ended up meeting at the portal area. "Wait for me here," William knew it was time to go and explore the portal area, "if I didn't show up in a day, go down and you'll find the portal ready."
He knew he might end up activating the portal before everyone would descend and join him. He left a few of his friends behind, to have someone to contact if he wanted to let them come down and join him.
He knew there wasn't a single danger down there from Karoline, and knew the right way to descend as well. It was a weird way, by just jumping off and falling over the central portal.