Hi David,
Reading in between the lines, I think you have guessed that to access your backup, you need to log in to the website http://updraftplus.com - is that what you're thinking?
If so, then this page would be relevant: http://updraftplus.com/faqs/please-can-mr-updraftplus-send-mr-customer-copy-backup-set-thanks/
Logging in at updraftplus.com doesn't have anything to do with your regular backups. Your backups aren't stored there, and you don't have an account there.
Best wishes,
David