In this situation, are you required to stop the vehicle in front of the pedestrian crossing?

Why?

The B-20 STOP sign concerns entry onto the priority road and does not itself require a stop before the pedestrian crossing. You must stop at the designated point or, if none is marked, before the priority road where you can assess traffic. You must stop before the crossing if necessary to give way to a pedestrian or because traffic conditions require it.

§ 21 ust. 1 i 2 rozporządzenia w sprawie znaków i sygnałów drogowych