Minecraft folder does not exist

I hope I have posted this to the right category, but I desperately need help.

I created a minecraft server using MineOS within TrueNAS. I am trying to make this a modded minecraft server, however when navigating the /var folder, there is no Minecraft folder to be found, even when the server is running with just default settings.

I cannot find an answer anywhere to this, no tutorial that is clear, at all.