Unable to answer "Do you have to pay to use this restroom?" – on level 0: Restroom – https://osm.org/node/10128409135 via StreetComplete 58.2:

WC ev. nur für Behinderte zugänglich. Tür ist versperrt, unklar, wo Schlüssel zu holen wäre.

Attached photo(s):
https://westnordost.de/p/227250.jpg