Steam to Steam multiplayer doesn't work for me and my buddies. I run a gaming community of few hundred players on Steam/Discord and i suggested we start playing Grounded together, no one is able to join each other through Steam, we have players from all over Europe and US, we all use Steam and we are not able to join each others world, we are able to see the world our friend has created and we are able to enter the password too, but after that we always get the same message that the world you are trying to enter does not exist anymore. None of us are logged in with Xbox account and none of us want to do that, but what i understood is that the multiplayer should still work between Steam users without having to log in.

I went to Steam forums and i found that someone random has had the same problem before too. With the title "Error: The game you are trying to join no longer exists"

Same