How do I set up an Unturned server?

Your server installs and starts on its own after you order it, so there is nothing to run yourself. The first start takes a few minutes longer than later ones, because the server downloads the Unturned game files from Steam before it can load a map. Watch the Console page: the server is fully up when it prints Loading level: 100%.

The settings you are most likely to change live on the Startup page, not in a config file. Server Name is what players see in the server browser and in the Connect Directly menu, and it is limited to 50 characters. Map chooses which official map loads, and defaults to PEI. Both take effect on the next restart.

Auto Update is on by default and runs a Steam update check on every boot. That keeps you current with the game, which matters in Unturned because players on a newer client cannot join an older server. If you would rather your server booted faster and stayed on a pinned build, set it to 0.

Additional Arguments passes extra launch flags through to the server exactly as you type them. Leave it blank for a working public server. The two flags most people want are -GSLT <token> to appear in the Steam server list and -Password <yourpassword> to make the server private. These are deliberately not separate fields: an empty value would be passed through as a bare flag, swallow the next argument, and crash the server on boot.

Some settings are fixed and not editable, including the internal server folder name and the Steam App ID. That is on purpose; changing the folder name would start a brand new world and orphan your existing one.