Servarr is a suite of tools designed to index and download torrents.
Sonarr has a install script. Run curl -o- https://raw.githubusercontent.com/Sonarr/Sonarr/develop/distribution/debian/install.sh | sudo bash or wget -qO- https://raw.githubusercontent.com/Sonarr/Sonarr/develop/distribution/debian/install.sh | sudo bash depending if you want to use curl or wget. That’s all! The script will walk you through the installation.
Unlike Sonarr, Radarr has no “offical” installation script. There is a community install script for Radarr and other tools in the Servarr suite. Run curl -o servarr-install-script.sh https://raw.githubusercontent.com/Servarr/Wiki/master/servarr/servarr-install-script.sh and then sudo bash servarr-install-script.sh to install and run the script. Then follow the instructions to install Radarr.
Just like Radarr, Prowlarr can be installed via the community installation script. Follow the same instructions in the Radarr section and select Prowlarr instead.
Prowlarr should be set up before Radarr and Sonarr, since Radarr and Sonarr rely on Prowlarr to find content. Setting up is pretty easy - add indexers and in the connections page add Radarr and Sonarr. You will need their API keys, found in each’s settings page.