I am trying to setup a newly received computer and have been given this prompt:

I have redacted the actual number for privacy reasons but to confirm, when I dial +61 and the number that is redacted, I am able to call the number successfully. This leads me to believe the number is fine.
When I click next, sometimes the 'Additional details' will disappear, but otherwise the screen stays the same.
I do not receive a phone call.
The error message has not been particularly useful in illuminating the problem here so I was wondering if anybody is able to provide some insight.