If you are a
DVC member it's free. There are slots for money, but you just push in the lever without coins and the machines work.
The laundry is on the bottom floor. Leaving the elevators, the exercise room is directly in front of you. Turn right and go down the hallway just a bit and the laundry room will be on your left.
If you have a 1 bedroom or larger, there's a washer/dryer in your villa. It's only the studio residents who need to use the laundry room.