How would I be able to make a successful soviet invasion?

I am trying to invade Soviet Union as the German Reich, I always get to the historical 1940 Europe map as Germany but once I try to invade the soviets its very difficult for me. My main issue is division templates, I don't know how people can make armies full of medium tanks. Is there a specific time I have to start making them? A specific way? I can't get them fast enough, I try to change division templates to a few divisions but the supplies will not deliver quickly enough. What do I do? Please answer if you can, thank you