Do you need a reservation for the pool? If check in is at 4pm, how does that work if you want to use that same day?

My apology im not sure call and ask

Get up early and wait in line good luck

And if you come in or check in @4pm you can ask the front desk if there's an opening if not go in line the next day or morning..

You can use it that day or the next day

You just have to go to the front desk and see if they have an opening. Typically ppl get in line at 730am and reserve a spot and time for the pool use.