Issues Reinstalling DVD version - Product key Already Used

I have MS Flight Sim (downloaded 11 Jan 2021). When started up today, there was an auto-update of 1.43GB which failed 3 times after downloading 1.3GB. This happened 4 times so no update. Then I couldn’t escape from that to the game and a warning window appeared saying if cancelled the download the program would be uninstalled. This has happened and I now do not have the program. When I check my MS account it reports that the Product Key has been redeemed (which is true). I need to find a way to reinstall the program with a download again. Can anyone help, please? I’ve installed other stuff before from within the game with no problem. This happened on the load-up screen and offered no help.