If you’re not comfortable with this, in my opinion you have the following options (in my preffered order):
- setup a new machine as per documentation but with a package installation (then stop the old instance, backup, restore #profit)
- get a workshop with Zammad to do this (no matter in which direction, but it’s pricey so no pressure…!)
- Fiddle your way around with the source code installation
I’m afraid I can’t hold your hand in this process.