Sonoff in HA OS supervisor missing?

New on HA. HA OS in virtualbox on linux Mint. Trying to follow sonoff How SONOFF Works with Home Assistant - SONOFF Official but it fail at once as i dont supervisor find Supervisor in the left menu. Supervisor it started in the HA terminal window. is there any better and never youtube or instruction as Sonoffs sucks/old?

Their guide is very outdated, a lot has changed in the nearly 2 years since that was written, including major re-arranging of the menus.

You can however use the search feature by pressing c and then start typing add (for add-ons) and it should find you the relevant menu. Or, follow the docs and find them in the settings menu.

A better way is to use sonoff lan