Do you legitimately qualify to use that site? If you don't, then you may have ran into hardware issues.
I'm assuming username cherold doesn't use assistive technologies with Windows.
What hardware issues could there be?
Cherold, Assistive technologies for Windows use special speech recognition, screen readers, etc for individuals who cannot use windows without them. I'm assuming you thought that since you missed the "free upgrade" offer, this would do no harm as it has to be the same upgrade - no, it's a totally different upgrade that is specifically made for the assistive technologies out there for people who have a major disability. Here are examples of the "assistive technologies": https://www.microsoft.com/enable/at/
I'm surprised that if your PC did not have assistive technologies installed that the upgrade actually happened - it should've scanned your PC for compatibility with the assistive technologies on your PC and found none then kicked you off the site telling you that your system does not qualify for the free upgade - or "Windows did not detect any assistive technologies on your system, your PC does not qualify for this upgrade"
I'm not a computer expert, but I'm assuming that the upgrade is trying to install drivers for software that doesn't exist on your system, therefore it's "hung up" searching for the software. I do not believe there is a "roll back" feature to undo an upgrade during the upgrade process itself.