Testing Multiplayer - Kvan7/Multiplayer-Starter GitHub Wiki
So how do you actually test this and see if multiplayer works? You can fully test this locally, almost. The only part that cant be tested locally without another computer is joining via Steam. To test locally you use the KCP Network Manager and ParrelSync. The KCP Network can run on localhost which allows another computer to connect super easily. If you want to test on the same computer, you can use ParrelSync to open another instance of the unity editor in read only to have another game running.
Above is the KCP Hud, by clicking host you create a server and join it on your side. Then on another instance you click client and will spawn in.