As far as i can see the server version is installed much the same way as FTB style servers. So you should be able to install it. The setup they describe in their instructions is for a standalone server, not for a server administered by MineOS (or any other Minecraft server admin tool).
It has a few prerequisites:
- a vanilla server jar
- the installer jar from Fabric
How to install:
- in MineOS: create new server
- in MineOS: use profile: mojang 1.15
- in MineOS: press button “copy server files”
do not start server (not needed now)
- in any sFTP program: manually copy fabric server installer into the created server directory
- in SSH: use command “cp minecraft_server.[version].jar server.jar” (without quotation marks)
- in SSH: run “java -jar fabric-installer-[version number].jar server” (without quotation marks)
Wait untill done
- in MineOS: in jar dropdown menu: chose server jar: “fabric-server-launch.jar”
- in MineOS: press button “accept EULA” and select “start”
This should do it, but the server need to do some stuff on first start, so be patient.
As always: You may need to stop server again to edit settings files to mach your needs.