Assess and prepare floor
The cured anhydrite screed will have a layer of laitance that will need to be removed after 2-6 days (dependent on brand of screed used). This will provide a dense surface to tile onto and will aid drying.
Ensure the floor is fully dry - the residual moisture level should be less than 0.5%. Drying times vary according to the brand of screed used. Some are designed for fast-track use, whilst others require the standard drying times. If no other information is available assume the screed will take 1 day per mm up to 40mm in thickness to dry in normal conditions. Screeds thicker than 40mm will require 2 days per mm.
Seal the floor with weber PR360 repeatedly until no more is absorbed and allow the primer to dry before tiling. An uncoupling membrane can be used to reduce stress on the tiling layer and to ensure that ettringite does not cause a failure.