How to add mods to your ARMA 3 server.
1 Open workshop on Steam for Arma 3.
2. Subscribe to the desired mod.

3 After the mod has downloaded, open Arma 3 and choose mods.

4. Select the mod and click Open Folder.

5. Compress the folder of the desired mod.

5. Stop the server.

6. Go to the File Manager on the Kinetic Panel.

7. Upload the .zip and drag the zipped file into the file manager.
8 Unarchive the zip. Copy the name of the file
9. Go to the Settings on the Kinetic Panel.

10 Locate the Additional mods box
and put in the file name.

11. Go back to the mod folder on your computer. Open the Keys folder.
12. Go to the File Manager on the Kinetic Panel.

13 Upload the mod keys.
11 Start your server

Issues that may occur
Zip, when uploaded ,is empty
This can happen if the mods folder is located on another drive. To fix this, open the mods folder on your PC. Create a new folder and name it @ModsName, then copy the contents of the original mods folder into it. After that, compress the new folder and upload it.