Docker on Libreelec (invalid reference)

Hey everyone, I’m very new to docker and was just trying to setup aria2 on my RPi4 running Libreelec. I’m struggling to install this image https://hub.docker.com/r/fanningert/aria2-with-webui/

I’m using this to try and run it however i’m getting an invalid reference format when i try and send it.

docker run -d --name unraid-aria2-with-webui -p 6800:6800 -p 6880:80 -v /root/var/media/external media/conf/ -v /DOWNLOAD_DIR:/root/var/media/external media/downloading/ -v /COMPLETED_DIR:/root/var/media/external media/downloaded/ -e SECRET=pass fanningert/aria2-with-webui

Any help would be appreciated. Sorry if there is something else i need to include, i’ve never touched docker before.