CO-OP question about SD

So can you explain how to get co-op working? I hosted, invited my son and it logged him in, and said he had joined my game but then it said something about a controller. His screen just became my screen and he could even see me moving my mouse. That can’t be right can it? I mean he’s on his PC so no way he has to use a controller, right. I mean that would just be dumb and I can’t think of any sane reason for it to be that way, right? So I’m afraid my update didn’t come in or something.I mean almost all these survivor games have co-op mode so it shouldn’t be that difficult for me to figure out. No way this can be as bad as Ark LOL.
But if you could go thru the steps to host a local game and get my son on I’d truly appreciate it.

Hi wolfhors3,

Can you provide the exact message about the controller please?

Sounded like you activated remote play rather than co-oping. As far as I know you can’t invite through steam friends list yet, you have to send the code when you start a online session.