i stayed in a similar camp near Soltau, I think it was an old German Camp for Soldiers/police or forest wardens. Used for a troop shelter.
There was one on Luneburger area (might even have een Saltau) which was like a hunting lodge complete with fire, that we used one winter. Took us hours to get an earth spike out on that ex, had to dig the fcuker out.
There weren't any "extermination camps" built in Germany it self.
Any number of concentration camps or labour camps and the like though.
Even in the middle of cities some buildings would be used to hold slave labourers so might have been something like that I suppose.
There were quite a few old farm houses/yards utelised by firing units and the German Range guys! Over the other side near Hohne was a transit camp mainly used by the Hun during there time on the ranges and over on the Fally side IVO Ostenholz is another one, again used by them!