Hi!
Probably it has to do with the permissions under which your external drive is mounted. The user that runs filebrowser should be the same user under whom the drive is mounted. That said, if you have a headless system (no display), probably you have to take care of permissions yourself. Beware that different filesystem types require different command line options (in the mount command). If you need more help, it would be nice to know your setup and always happy to help :)

I more was referring to how to have filebrowser see the external drive. What do i modify to add the drive into Filebrowser?
How can I run filebrowser with the external drive as the only storage it uses?

$ filebrowser -r /mnt/your-drive-name -p port_number_here -a address_here

And that is put in the docker terminal or where is that command entered?
Sorry, total new user here

Ohh sorry for that... I didn't understand that you use docker. The command above is supposed to work if you have installed filebrowser in your system. Not if you use docker container. I suggest you check this link: https://filebrowser.org/installation . It has the specific commands for linux and for docker. My recommendation is that you should not use docker.