Avogadro 1 is not under active development, the repository was archived in September 2021. Development of Avogadro 2 is being done at https://github.com/openchemistry/avogadrolibs. Avogadro is an advanced molecular editor designed for cross-platform use in computational chemistry, molecular modeling, bioinformatics, materials science, and related areas.
When I click on Build menu in menu bar, nothing shows up.
Avogadro 1.2.0 + Ubuntu 19.10 Installed with
apt install avogadro, translated to Polish.