Installing the Modpack on Servers

First, you need to download the unsup_setup script compatible with your system.
If you're on Windows, use this link.
If you're on Linux or MacOS, use this link.

Then, move the unsup_setup script to your server's root folder (the folder that has your server .jar) and run it, then add the following to your unix_args.txt file.

-javaagent:unsup.jar

You'll also want to add the following line to your unsup.ini file, under preset=minecraft.

no_gui=true

After this, I recommend following the post-install guide.