Contact the Welcome Hall Land Berlin in the large white tent by the central station (Hauptbahnhof). Or at the arrival center at Ankunftszentrum TXL (Ukraine). There is a shuttle service from HBF Central Station.
We understand that there may be long queues in the center, and you may have to seek help from volunteers. Please take care of your own safety, inform your relatives with whom and where you spend the night, and check the documents.
Rent: Ukrainians look for flats or rooms to rent just like anyone else. Sozialämter can cover your rent if you give them this agreement during your meetings. The flat must be of a value that the state can cover.
Regarding social housing. Yes, there is social housing in Germany for socially disadvantaged people. You DON’T NEED it yet. You can only get such flats with a WBS certificate, and that is a separate process.