Unable to answer "What are the opening hours here?" for https://osm.org/node/7687401629 via StreetComplete 49.0:

On the left (suite A) there is "Studio 17" and on the right (suite B) there is Agony Books. This photo was posted on the center door, so I presume there used to be a rental office in one of these spaces

Attached photo(s):
https://westnordost.de/p/120725.jpg