what is the “key word” for downloading something in the terminal? For example to archLinux is pacman 
‘flatpak’ e.g.
flatpak install flathub org.gnome.bijiben
then
flatpak run org.gnome.bijiben
if you want the app to appear on the desktop after you’ve added it on the command line you need to manually add it with the App Center (it should be in the ‘Installed’ list) or run it using the command line or search.