It should be seemless if you follow the game framework conventions, multiplayer in UE4 works based on state replication where client submit player state to server, server has master state and syncs client, in other words the engine tries to make a illusion that everyone runs on same machine. In most cases you don’t need to interfare but you can control the replication process, sometimes you forced, because GameMode is only on server and PlayerController is only in client that it represent and server, so sometimes you need to bridge data somehow. here a docs with replication
I didnt read tutorial you gave, but first try running it on server and connect to it with another client, see how it works