"Website does not list the location any longer, and doesn't seem to exist in reality either"
The place has gone or never existed. A user of Organic Maps application has reported that the POI was visible on the map (see snapshot date below), but was not found on the ground.
OSM snapshot date: 2026-03-10T00:09:11Z
POI name: SATS Vasagatan
POI types: leisure-fitness_centre
#organicmaps android 2026.03.12-2-FDroid

"Corrected the adress to 12 from 12A, since the building has multiple doors"
OSM snapshot date: 2024-05-28T17:19:44Z
POI has no name
POI types: building
#organicmaps android