Absolute Beginners guide to installing HA on Intel NUC using Docker

I followed https://www.juanmtech.com/set-up-hassio-in-docker-and-in-an-ubuntu-server/, in which I think the key command is
curl -sL "https://raw.githubusercontent.com/home-assistant/hassio-installer/master/hassio_install.sh" | bash -s

I must seem a bit deaf but as I’m seeing DROP rules in IPtables I think these rules must drop something, no ? As also I see forward rules, I thought these rules were mandatory for things to work.

As suggested in

I tried changing port number (51829) and I’d like to forward this port to see if it works.