We got a text about an hour before our arrival time letting us know our exact room number. I knew the building number from that so I knew which direction to head. And there are signs all over the resort with directions to each building as well as signs at each building so you know which room numbers are which floor. The room number actually identifies the exact location. I *think* the first digit is the building number; second is the floor number; and the last 2 are the room number. So a room number of 6423 would be building 6; 4th floor; room 23 (though the room number at the door will still say 6423) We also got an e-mail prior to arrival (but after the text) that included a map of the resort. But just to be safe, I had saved a copy of the map on my phone before we left.
ETA: Actually, the 2nd digit of the room number will be a 5, 6, 7, or 8 which indicates floors 1-4. 5= 1st floor; 6 = 2nd floor, etc. here's part of the text from the e-mail we got just prior to arrival last summer:
Don’t forget, if you already have your MagicBand, you can go directly to your room without stopping at the front desk! Our Bell Services team will be available to assist you with your luggage upon arrival.
Your Disney Resort hotel: Disney's Art of Animation Resort
Your Resort area: Wide World of Sports Resort Area
Your room number: 6805
Your room location: 4th FloorLion KingBuilding 6
Click here to view a map of your Resort hotel.