Is drainage necessary under the entrance platform?

Well, whether there is only a thin film of moisture on it due to a roof or water standing on it by the centimeter probably doesn't matter for small cracks where it could penetrate. I, as a layman in construction but someone who understands physics, would say that the mortar and the joint compound must be applied in such a way that no cracks occur. Anyway. Maybe thinner? At least not "earth moist"!

One could also make the podium plate from one piece. Then there are no joints and the matter is settled. Our entrance podium is made from one piece.

ps: the link above is not allowed here in the forum.

You still have connection joints

Sorry about the link, I can't delete it anymore either. Speaking of joints. For the 60x60 large tiles and 3cm thickness, how "thin" can the joints be to prevent cracks or gaps? Is below 5mm possible?

You still have connection joints

where except directly at the front door? this one is covered

But not with the OP, and a roof only provides limited protection against driving rain or snow - even if it represents extreme cases.

And yes, I meant exactly this joint.