RPi3B+ Booting from SSD-USB - Python Docker - Need help install Supervisor (Hass.io) Link

Hi there, I’ve recently had to rebuild my RPi3B+ from scratch and successfully booting from USB SSD. Installed Python Virtual environment with Docker. Installed Homeassistant using this guide providing me with access to a working solution except I cannot access Supervisor (aka Hass.io) link. I origionally had this working with Supervisor some months ago but the link to guide no longe works. Despite having searched through this forum I just can’t configure/install a working solution. I appreciate that this has probably been requested many times but any help would be appreciated. (I’m a novice re Linux and HA)

My setup is: Raspberry Pi 3B+ booting from an Samsung 64Gb USB SSD with OS Raspbian v10 but if more details required then please ask.