Registration Device error - Article 121699 not existing

And then I get the above if i hit retry.

I tried multiple times, same end results.

The article quoted is wrong and we are getting it fixed. The correct article for activation and registration errors can be found here: community.sophos.com/.../122496. 

Although the error you are getting is generic, it is worth checking the various suggested 'What to do' sections in the 'Error code' tab in the article, e.g. to ensure that your device has internet connectivity as, without that, Activation / Registration will not work.