I have found a solution.
I was using an old iPhone 6s. This morning I updated my iPad to 13.2.3 and it works.
It went through the accessing account stage and I have now happily linked my account to one of my CCU. Happy days.
Try following the instructions I posted above.
I was having the same issues, after trying several different things I think the way I resolved it was that I turned off power saving mode on my Samsung galaxy s9.
Hope this helps.