For Linux user only.
No need to compile from source anymore! Avogadro is available in Flatpak format, you can now install from Flathub.
Read setup guide to setup Flatpak before installing.
If your software manager support installing Flatpak, try it first.
Install it with
flatpak install flathub org.openchemistry.Avogadro2
Avogadro2 icon should appear in your desktop menu.