If you think that's overkill for an AA platform, you haven't met the Wirbelwind.
Incidentally, those AA guns are 2 cm Flakvierling 38. So, yes, they are literally carrying Flak cannons.
Edit: If anyone wants to know, it's the Möbelwagen prototype with the aforementioned 2 cm Flakvierling 38 turret. Due to its inferior performance, the second variant used the 3.7 cm Flak 43 L/89 as its main armament.