Changing scene with lobby

I downloaded this project made by codeMonkey, its a lobby project.

Now I want to spawn the players in the game after the host decide to start the game. CodeMonkey actually did a tutorial showing this part, but it uses relay, and in my game Im not going to use this resource.
I tried to use the loadscene method (by the scenemanager class) but I dont think its a good approach, mainly because I didnt spawn the player prefabs…
Is there any other way to do this? If not, how can I change the scene and then create the player prefabs?