Ghost iPhone preventing iCloud access on iPad 2

I am trying to use an old iPad 2 (version iOS 9.3.5) purely as a second screen reading device - so basic functions. It still works just clearly doesn't update and slow but should be enough to log on to a browser and read articles and instructions while I work on a laptop.

It's an old gifted one that's been returned to factory settings.

But when I try and add my account to it, I can add iTunes but not iCloud. Instead a message comes up telling me that when I put in my account and password there is another step:

Enter Passcode for Other iPhone

Access to your account is protected by the passcode for "Dhruti's iPhone". Your passcode is encrypted and cannot be read by Apple.'

But I don't have an iphone and when I look to see what accounts are connected to my account, it's purely the ipad in question, so I can't even disconnect the iphone as there isn't one connected to my user account.

I get the verification codes to my current phone which is android. I don't even know what phone it is referring to and I certainly don't have access to it. I have looked elsewhere for answers which say remove the two step verification in place to get the messages on my phone but there's no option to disable that as it's set up and I don't know how to remove 'Dhruti's iPhone' (which doesn't exist) from my user account. Would I need to go into store? Is there anywhere to go to remove the imaginary iphone from my account?

The gifted ipad is clean and the person who owned it doesn't have it connected to their settings.

[Edited by Moderator]