Satisfying, the factory simulator that challenges you to create complex arrays of machines released today on Steam, and the good news is that it supports cross-platform play between Steam and the Epic Games Store. This means that new players on Steam can enjoy the game with friends who have already played on the EGS.
The easiest way to play with your friends is to use a hosted session that they can join using the session ID. Multiplayer in Satisfactory is peer to peer, hosted by one of the players in the group. If there are more than two players in the party, choose the player who is closest to everyone.
They can host your own game by changing the settings when you load into your saved game. Open the menu and click on Manage session. Change the session type to friends only to allow your friends to join. If the game is set to Private, people can only join if you send them an invite. Press the "Copy to clipboard" button to copy the session ID, and then you can send it to the person you want to play with.
The game currently has no plan for public sessions, in order to avoid any possible issues. It's also worth noting that multiplayer isn't exactly stable at the moment, as the game is still in Early Access, and bugs and performance issues are quite common. Add the fact that cross-platform play can be a bit uncertain, again because the game is in beta, and you might run into some issues.
If that happens, it will have to be accepted as a risk to play early access titles, although we're sure the developers would appreciate any bug reports you send.