Adding mods to your Project Zomboid server should be easy. Just follow these steps.
On the game panel navigate to “Configuration Files” and edit server\Zomboid\Server\serverPZ.ini
Locate the “WorkshopItems=” line and add the Steam Workshop ID (found at the end of the URL of the mod's Steam Workshop) in a semi-colon ; separated string.
In the same file, find the following line: “Mods=”
The value needed for this section can often be found in the description of the mod on the Steam Workshop page.
”Workshop ID: 123456789
Mod ID: ModName1”
Once you have that value you can insert it like this:
Save the file and restart your server.
The mods should now be activated on your server.