Often times you will want to run a server that uses less resources.
To run a Unity application like this you will want to launch it with arguments
You can do this in command line, for example
myGame.exe -batchmode -nographics.
Your game then needs to check if it is running headless.
With this script in your initial scene, you can enter
myGame.exe -batchmode -nographics -map Level1 and it will launch a server for your scene "Level1".
Of course you can customize this to use a port you enter, a different game mode, etc. by making more argument checks.
You will also want to disable things in the game when running headless such as locking the cursor, spawning a player, and music.
For the tutorial there is
Screen.lockCursor = true in "PlayerCamera.cs", you can modify the script to only lock the cursor if not in headless mode.
The same goes for
Player.serverPlayer.InstantiateEntity() in "ServerCallbacks.cs"