To get the latest bleeding edge Octopi code all you need to do is run:
git clone https://github.com/aarnt/octopi.git
And after you have Octopi’s repository you can compile it just running:
cd ./octopi; qmake-qt5; make
If you use Arch Linux with an AUR tool you can grab Octopi by the “octopi” (stable) or “octopi-git” (dev) packages, thanks to the great community.
Manjaro Linux and KaOS have Octopi natively in their repositories.