The recommended way to get Déjà Dup.
sudo apt install deja-dup
sudo dnf install deja-dup
You can download a source tarball and compile it yourself. Note that this is an advanced use case. It's easier to get the supported release from your distribution.
Be careful here! An unstable backup program is not generally a wise thing to rely on. But we love any and all help testing upcoming releases!
sudo add-apt-repository -u ppa:deja-dup-team/testing sudo apt install deja-dup
git clone https://gitlab.gnome.org/World/deja-dup.git