TLDR; I managed to get 4 player split screen co-op to "work". Results are SUPER buggy, but it doesn't seem like it would take too much effort to integrate it properly.
I had the exact same issue as the screenshot in the first post of this topic. To replicate this follow these steps:
1. 4 people create profiles by pressing start on their 4 separate controllers in the main menu.
2. At this point each controller is assigned a profile, and can be seen on the lefthand side of the main menu screen.
3. Start a new story single player story mode game.
4. You should see the same screen as the OP. Congrats.
This creates a broken experience where 4 people are attempting to create characters on a single screen, which frankly, if the devs don't want you doing, they should not allow you to even get this far. No amount of struggling with this janky interface allowed us to create our characters. However, I did manage to work my way around it using the following steps:
1. Start up a main instance of the game (through steam or whatever client you are using).
2. Use the game executable (can't use the steam shortcut) to start 3 more instance of the game.
3. In the main instance start a new story MULTIPLAYER game opened up to the LAN.
4. Join the multiplayer game with the 3 other instance of the game. Ready all instances.
5. This should let you create all four of your campaign characters. When you are done click Start Game in all four instances.
6. The game will start, once it gets to a place you can save, save the game on the main host instance.
7. Close all instances of the game
8. Start up the game through the main method again (steam, etc.).
9. Press start on all the controllers and have them use a profile, preferably the one created in the first set of steps above.
10. Continue/load the game, using the save you created in step 6.
11. Press start, use the Party Management (i think that is what it is called, not near my game pc atm) option to assign the correct character to the correct controller.
Congrats, you can play Divinity Original Sin 2's promised 4 player mode, in a single screen. Except for the following issues, which are MAJOR.
1.The split screen only splits twice. Players 3 and 4 don't have their own camera.
2. When the screen splits players 2, 3, and 4 share the right side of the screen, with their interfaces overlapping.
3. Also when the screen splits, players 3 and 4's control directions screw up. They remain linked to the perspective of player 1's camera rotation.
This could all be fixed by splitting the screen horizontally and applying player 3 and 4's interfaces to the additional 2 screens, as well as any dialogs and popups. Just give us 4 player couch co-op, you are so close anyway... let me worry about the performance issues.