I have had to replace the HD in an old but perfectly serviceable 27" iMac. The latest software it will run is macOS 13.6. I just need it for a bit of lightweight spreadsheet and wp work. I KNOW it is not state of the art but I am not trying to render massive 3d scenes - it is perfectly adequate and has a nice big display.
I have stumped up the money for a MS365 subscription (I use this on another machine) and it specifically states that it is compatible with macOS13.6
Once I have downloaded the 1.8GB of application, it won't install as the installer specifically states that macOS 10.14 or greater is required.
I also have paid for copy of Microsoft 2011 which is perfectly adequate for my needs on this machine but the activation server has been switched off so I am not even allowed to downgrade.
It would be helpful if Microsoft updated the misleading information and would stop people wasting their time.
This sort of practice is not sustainable - we cannot require people to keep replacing machines year on year.