In this guide
Download the mod
Go To mod.io/g/corekeeper.
Find the mod you want to add to the server.
Scroll down on the right panel and download the mod manually.
Create the Mods Folder
To note the mods & modloader folders in the root is just for mod configs and not for the mods themselves!
Go to File Manager [[UUID_LINK:files|here]].
Navigate to "CoreKeeperServer_Data > StreamingAssets" [[UUID_LINK:files#/CoreKeeperServer_Data/StreamingAssets|here]] and create a "Mods" folder.
Each mod will need it's own folder and the folder names are arbitrary, so for example the mod Enemy Health Bars.
Create a folder in "Mods" called "Health Bars".
Drag the .zip that was downloaded from mod.io into "Health Bars".
Unarchive the .zip, It should look something like this:
The mod is installed!
Notes
If your server was running you'll have to restart it to apply the mod.
If you or one of your friends doesn't have a server-side mod installed they will not be able to join the server, though client sided mods are fine.