What should you do in this situation?

You answered correctly by choosing to allow the pedestrian to cross and waiting on your side of the pedestrian crossing until the blue vehicle has completed its turn.

In German traffic rules, pedestrians at a marked pedestrian crossing have the right of way. You must stop and let them cross safely. Additionally, since the blue vehicle is turning right, you should not pull up directly behind it on the crossing because this could block or endanger the pedestrian crossing.

Waiting on your side of the crossing ensures the area remains clear for pedestrians and respects their right of way, while also allowing the blue vehicle to make its turn safely. This behavior follows the principle of yielding to both pedestrians and turning traffic at pedestrian crossings.