The game is not polished enough to have a multiplayer yet, also its not that easy to make multiplayer at first place, its an unreal engine game
If you want multiplayer, you have to get VoidTogether mod, but thats on older version of the game and its just a sandbox, the guy behind the mod said that its really difficult to sync all the things, like doors, props, story ect...
you can find it here: https://thunderstore.io/c/voices-of-the-void/p/Gatohost/VoidTogether/