I would say it is a good mile or so walk, maybe a mile and a half. If you catch the bus just right I would say 10 or 15 minutes. If you have to wait for the bus a little longer. If you have a golf cart you can be there in minutes.
I'm not sure why it would take 15-20 minutes. We stayed in the 2000 loop and buses came very quickly and we got off the bus in about 3 minutes or less and walked for about 1-2 minutes. I love the convenience of the buses internally.