install systemd unit in /etc/systemd/system, change User option to preferred user
create minecraft server instances in ~/.local/share/mcserver/instances
- you can also symlink server directories from elsewhere on the system
- use instance/ as a starting point. you need, at minimum, a start.sh startup script that executes the server jar, the server jar itself and a vars file
systemctl enable --now mcserver@instancename

other info

there's a few other random things in the provided instance folder:

a start.sh which should work for most use cases
a merge.sh script to merge some of my default configs
a starting point for the vars file
an incomplete update_paper.py script that i was working on a few years ago but never finished
a completed eula.txt (i have no idea the legality of sharing a pre-completed eula, nor do i care)
a start.bat polyglot so that the server can also be used on windows
- this was mainly for server auto restart via plugins, but this is no longer needed with systemd