Hi, Alison!
Typically, Resort amenities are reserved for the use of Guests of that particular Resort. This is for included amenities like the pool, weight room, family activities, etc. Non-included experiences - like rentals, restaurants, lounges - are open to all Guests.
Disney's Pop Century Resort offers three heated pools for its Guests. While you're welcome to any of those three, you'll need to check with the lifeguard at Disney's Art of Animation Resort before you use that pool.
Please be aware that Cast Members do reserve the right to ask Guests for Resort identification at these amenities to ensure that Guests of that particular Resort are given priority.
Have a great time at Disney's fabulous new
Art of Animation Resort!
See you later, celebrator,
-Deborah B.