The Auto transmission is a"lifetime fill".
What means that you don't change it until your transmission breaks.
Of course, your transmission will break sooner if you don't change the transmission fluid.
The transmission fluid has to be checked from underneath the car, with the car perfectly level, and the transmission fluid warmed up slightly. Generally I leave this to a local garage that specializes in Audis.
While you are at it, you may want to change a few quarts of transmission fluid, the fluids from the center differential and rear differential. Bleed the brakes. get a turkey baster and swap out the power steering fluid. Use new Pentosin 11 fluid only. Top up the battery with distilled water, drain your radiator and re-fill with new pink antifreeze and distilled water.