Hi and welcome: The Constellation tiles from Ann Sacks should not present any particular difficulties with installation. I am a little perplexed that the installation instructions I found for the Constellation calls for Mapei’s Adesilex P10, a product that as far as I can tell does not exist in North America (I am assuming you live somewhere in NA). Continuing with this thought however, Primer S is specified to keep the adhesive from drying too quickly, and it will not provide any anti fracture properties for the job. Unfortunately I have to provide alternative instructions from the instructions Ann Sacks has posted: I would purchase Granirapid white adhesive from Mapei and install the tiles over a good anti-fracture membrane. My preference is for the “peel and stick” variety such as available from Protecto Wrap or Mapei. Coincidentally, the anti-fracture membrane also calls for a sealer over any drywall surface. The reason for insisting on anti fracture is because we feel it is reasonable insurance against cracks and moisture penetration for a small additional fee.