If you are not sure how this is done, please take a look here.

Create a Custom Commandline, or Edit an existing one. Log into the TCAdmin control panel using the details sent to you when you purchased the server. Please don’t punish me for choosing GOG as my platform to experience your game. Adding a Steam Workshop Collection to your server is very easy and can be used to add mods/maps and other settings to your server. I love modding and I love Battle Brothers, it’s one of the best tactical games I’ve played period. As a tradeoff you get no control over your mods whatsoever, the author can remove them or update them in a way that you don’t like and your Steam Workshop subscription will adjust the mod installation to reflect the latest change without your input. The only thing that Steam Workshop offers is a one-click installation process if you’re gaming on Steam. Nexusmods has been the go-to mod page for years and years and is open to everyone. It divides the community into first and second class citizen as far as mods are concerned. It’s a way for Valve to one-up the competition as it excludes those of us who buys games on other platforms such as GOG. Steam Workshop is an exclusivity deal just like what is going on right now with the Epic store. I want to plead with the devs to not support the Steam Workshop now that the game is opened up to mods.

Steam workshop how to install mods