Your way to us:

Vogtturm KasseCar: public underground garages and parking spaces in the town center (5 minutes on foot)
Bus: bus stop Zell am See / Postplatz (5 minutes on foot)
Train: Zell am See train station (8 minutes on foot through the pedestrian zone)
Bus travel: Parking lot next to the ice rink Zell am See (8 minutes walk)