This is a dockerised version of nzbget.
The container has three volumes, one for configuration, one for successfully downloaded files, and one for everything else (lock files, queue, intermediates, etc).
Create named volumes for the config and main dirs:
docker volume create --name nzbget-config
docker volume create --name nzbget-main
Start a container, exposing the UI port, and binding all the volumes:
docker run -d --name nzbget \
--restart always \
-v nzbget-config:/config \
-v nzbget-main:/maindir \
-v /mnt/external/downloads:/destination \
-p 6789:6789 \
csmith/nzbget:16.4