Yes they do, but the rings must be see-through. Not necessarily clear, they can be colored but they cannot by opaque. Disney also offers FREE life vests for children who can't swim at all resorts. I personally don't trust arm floaties. I don't think they are safe.
We stay at The Poly and The Contemporary, and my DD has always worn arm floats in the pool. In fact, she even wore them to Blizzard Beach and the lifeguards allowed it.