Mold in the new building?

Then air out at least 3 times a day for 10-15 minutes spread throughout the day (in the morning before you go to work, at noon after you come home from work, and in the evening before you go to sleep). Additionally, on specific occasions (after cooking, after showering). And always with completely opened windows. Keep an eye on the humidity with a hygrometer. It should always be between 50 and 60%. If it goes higher, air out again immediately. You should also heat the bedroom and dressing room. Otherwise, the air will not absorb the moisture properly.

Edit: was faster :)

Ok, I extend the ventilation period to 10-15 minutes. I can't say the exact temperature, I am heating at level 2 out of 6.

Thanks for your reply. :)

What do you think about desiccant dehumidifiers based on granule blocks?

The lower the air temperature, the less moisture the air can absorb and thus transport outside even during brief shock ventilation. Therefore, to my knowledge, rooms should always be kept above 15/16°.

All rooms are over 15/16°C, I estimate the bedrooms to be around 18°C.

What do you think about dehumidifiers based on granulate blocks?

Not much. You have too much moisture in the apartment for that. I am using a dehumidifier from Aktobis (WDH-520HB) for the basement. The power consumption is not as high as with the usual construction dryers, and it works quite well for me. However, I would not want to judge whether the device is powerful enough for your construction drying. If in doubt, you have to set up several.

Can I also set up the device in my hallway, open the doors to the other rooms, and then dehumidify centrally in one place? Or is it better to dehumidify one room (living room, bathroom, bedroom) each day? I don't want to buy several for the beginning.