[Imp]

Soviets early war anti tank capability is not good.

Lack of experience is a big problem generally.
Infantry has no AT capability just grenades, expect to see a lot of tank panic if assault.
Have to think about your artillery as its slow to react, this also makes placing smoke to cover moving AT guns hard.
Your AT weapons to hit is not the best & you don't get many shots to improve your chances.

You do get probably the most potent movable ATG though.

Your engineers can at least take on armor if they don't panic & also are your fast smoke screen for doing things undetected as they normally have a decent amount of it.

Its hard I seem to spend as much time falling back as going forward trying to avoid arty & draw them into mine.

Using just or mainly ATGs is hard slows the game down especially if assaulting but can be very effective if micro manage a bit.
Turn down ranges let them stroll in pound the eyes (infantry) then open up with hopefully 4-6 ATGs firing from different angles for a bit of carnage.

Lack of mobility does mean a much higher chance of things going very wrong because changing the plan takes time.

Mid war your experience improves & given the right terrain the infantry are capable of taking on tanks, not the best AT weaponry but it will do the job.