If it happens so that you do not have a mod in the joint party, you will have a notice saying that it must be added to the game. Now you can see the existing mods and begin the game.The button for managing mods appears when a solo or multi-player game is set up.
If you wish to download a mod, you have to click on Subscribe.In the workshop a player can view all mods.With this editor a player is able to manage various functions: viewing, editing, converting and uploading the selected mods using Steam workshop.“ Mudrunner 2 – Editor Beta” is the AppID tool name, you can access it via Steam library > Tools.
How To Create MudRunner Mods: using Editor tool