Add the following to the sources list:
deb-src http://raspbian.raspberrypi.org/raspbian/ buster main contrib non-free
Install with the following commands:
sudo apt-get update
sudo apt-get install sabnzbdplus unzip
sudo apt-get -y build-dep rar unrar-nonfree
sudo apt-get source -b unrar-nonfree
sudo dpkg -i unrar*.deb
Start the server as daemon:
sabnzbdplus --server 0.0.0.0 --daemon
Install with the following commands:
sudo apt-get update
sudo apt-get install python2.7 git-core -y
sudo git clone https://github.com/theotherp/nzbhydra /opt/nzbhydra
sudo chown -R pi:pi /opt/nzbhydra
Start the server as daemon:
python nzbhydra.py --host=0.0.0.0 --port=5057 --nobrowser --daemon
(Source: https://www.htpcguides.com/install-nzbhydra-debian-universal-usenet-searching/)