By default D:OS EE only supports 2 players. This mod is the same however you can modify your .exe file to support 4 players

Please see this guide and only do the hex edit modification to the host's exe file. The Meta file edit is already included in my mod.
http://steamcommunity.com/sharedfiles/filedetails/?id=548760493




Also during character creation you will run into this issue:

The problem is the mod can't handle 3 players connected at once during creation. I believe it's a problem caused by the game engine and there is nothing I can do about it. This is the workaround, it's janky but works:

So for example Player 1(host) and player 2 join.

Player 2 makes his character and both hit accept.

Then player 2 leaves and player 3 joins.

You assign player 3 to the 3rd connected player and he makes that character.

Do the same for the 4th player.

Hit accept and then player 2 and 3 can reconnect once you hit Cyseal Beach and you can assign characters accordingly.