Sealing against pressing water

They dried the screed and walls. We moved out because the ground floor was affected by mold and so they could start the restoration.

How exactly is the house positioned on the site? I'm having trouble imagining how so much water can push in. After all, there is a drainage strip around the house.
Again ... make sure to consult an expert before any further patchwork is done here.

Drainage is being installed only now! The soil is clayey and rainwater constantly accumulates

You are misunderstanding something. By drainage strips I do not mean the drainage pipes, but the gravel strip. With proper planning, water should not permanently stand against a house without a slab foundation, which is why I am also asking how the terrain is situated. I would avoid having a drainage system imposed on me if possible, as it needs to be cleaned regularly to prevent clogging.
I believe your house sits too low in the terrain and the house sealing was botched. The first is a planning error, the second is shoddy workmanship. And now they want to fix the shoddy work by smearing something on the front. But that will not work.
This is how it should look, for example. The details may vary slightly from manufacturer to manufacturer, so have the builder provide the appropriate one. You are entitled to this because the builder owes you a construction according to the manufacturer's specifications and the recognized rules of technology, which you can only verify by reviewing the detail (or having it reviewed).

Does it run through the building insurance?

I can unfortunately only confirm that. At the back of the garden, VW Immobilien installed a water channel before the house was built in such a way that the rainwater flows over the garden and ends up in a shaft. However, the house was set so deep that the channel is higher than the garden, and therefore the water stands in the garden. That is why the developer built a cistern with a submersible pump in the garden after the first water damage. Water from the roof flows via the downpipe into the cistern and is pumped out. If a drainage doesn’t help, what else should be done?