the 3576 is an analog locomotive with electronic regulated driving. it can not be controlled digitally.
it might have been upgraded already, so you should ask the seller.
if it has not been upgraded with a digital decoder, a 60906 decoder is one good economic option if you don't need sound. (since it's fitted with a 5 pole motor and a field coil.)

I think you can add a digital decoder to it Malvern! It already has a 5 pole high efficiency motor. My 3511 Klasse C was an analog 5 star and I put a non sound decoder in it. That was a bit tricky, because the motor is a Faulhaber can motor in the boiler, not like this railacr's regualar verticle 5 pole brush motor. If it has LED lights, all the better. Have a pro do the conversion because of the lighting and rewiring involved if possible, or someone can post or send you a schematic. You could probably even add diesel sound.