MiaB only supports installation on a fresh 22.04 install
If you are upgrading 20.04 to 22.04 some MiaB dependencies might not be taken into account. People have managed to make it work but it requires linux knowledge to figure out what is missing/broken and you might have issues further down the road so not recommended.
You can not install MiaB on 20.04
22.04 only supports v60 and above
18.04 only supports until v57a
if you need to install on alternative ubuntu/debian release best to look at GitHub - ddavness/power-mailinabox: A Mail-in-a-Box with extra capabilities and more customizability. Not just for power users! which is a fork