Game server is now available on the game's folder until the Free Game Server DLC is released in April.

Go to the game's folder/Datcha_Server and execute the server via world.exe.
Then open 'gamesfolder/data/Login.idx'
and add your local host like:

Northern America,216.189.148.53,8002
Local,127.0.0.1,8002

Open the game, select Local and login.

Enjoy,
Eren