Probably to get them to fill their days productively to pass the time until they could be deported.

Should apply to both. Although the only ones to get offended at the idea of real work were the pampered occupants kept sheltered from the war zones...

It was meant for the prisoners. Auschwitz was a work camp. As long as the prisoners did their jobs and didn't cause trouble, they were pretty much left alone to do as they pleased (within the confines of the camp). Yes, they were prisoners, and arguably 'slaves', but they were not being murdered.