Starting from Linux download page: https://linuxmint.com/download.php
chose to download from mirror site: advancedhosters.com
linuxmint-21-cinnamon-64bit.iso file was downloaded
I thought the install was finished, so connected the backup drive and started copying over all my files.
That process was interrupted by dialogue for package manager, asking to do updates.
I selected linux site and clicked update.
Got error that several packages could not be updated.
Closed dialogue box and continued with restoring backup files.