For those who want to play Total War: Warhammer II with all the DLCs on Steam, but don't want to buy them, the good old CreamAPI comes to the rescue.
1. Download all free DLCs on Steam! Otherwise, it will crash at the start of a new company. (It is very important)
2. Download DLC Unlocker for 1.12.1
3. Unpack the downloaded archive with the unlocker. From the unlocker folder, drop the files into the Total War: Warhammer II game folder with the replacement of files.
Archive password: cs.rin.ru
4. Play. There is nothing to be afraid of. This is a proven method available for many games for a long time.