After checking the rewards that he got from reaching Epic Grade, Aaron went to the dungeon.
Though Jay has said that it would take a day to collect the resources required to claim the dungeon for himself would take at least a day, he has to reach the core before that.
When one enters a wild dungeon, they would prepare the resources needed to claim the dungeon properly and transfer to another place. So, they would only need to clear the dungeon once, but that was not the situation that Aaron found himself in.
When he first found the dungeon, his mind was not on claiming the dungeon. It was on clearing the Rank-5 quest. Only after completing that did he think about the issue.
Since he didn't think about the claim, he didn't bring any resources to relocate it. So, now to relocate the dungeon, he has to clear it once again and reach the core that would be present in the Boss Room here.
If there were no boss, then it would be in the core room.
