First of all, make sure to refer and understand the general instructions from the official Verlihub documentation:
https://github.com/Verlihub/verlihub/wiki/Installation
What you'll find here are the specific instructions to compile Verlihub in a FreeBSD system, or in a TrueNAS jail. I'm considering that you already have a FreeBSD system or a jail ready to use. FreeBSD installation or jail creation will not be covered here.