you should add a singleplayer button instead of having to make a server to play alone
I understand that its multiplayer but what if you don't have friends
There is a hidden create game button in the game (that I use to play test), but the reason why it's hidden is because when players host and other join, it creates a whole bunch of bugs.
A workaround you can do right now is to run the server application (I'd recommend playing with the configurations and a simple password for the admin console) and then run the client application, and connect by typing in "localhost" in the IP input field.