Survival Multiplayer Questions about Respawn/log off

So how does this work exactly? I started playing on a survival server and started in a drop pod. I built some stuff, wind turbine, refinery etc… I logged off the server and came back an hour later and had to spawn all over again. What’s the point in this? What do I need to do to respawn where I left off? On my second run through I tried to build a medical bay, but don’t have any cobalt to finish building it. What gives? Any help would be appreciated!