We also have the Schwarze Wanne and the order for us was from bottom to top 1. Clean layer, 2. Bitumen + torch-on membrane, 3. Insulation, 4. Floor slab.
Above that, in my opinion, does not help, since the water would probably also rise up in the walls if it comes through the floor slab.
Therefore, damp-proof membranes should be placed under the walls. We also used the Katja.