iPad asking for a second verification, but other device does not provide a pop up

My dad had a work iPad, it was completely decommissioned by his company and then given him for personal use. When turning on the device it has the typical start up screen - hello in multiple languages, and asks if you want to restore from a backup, or set it up as a new device. I have tried both options, it does the typical ask for iCloud password (note that his Apple ID is currently his work email address, I don't know if that is the issue so thought I would mention it). We log in with his Apple ID, it asks for a verification code from another device. He has an iPhone, we verify, get a 6 digit code, enter it, it moves to another screen. Then it asks for us to approve it from another device that's also signed into the same Apple ID. This time his phone does NOT provide a pop up or other way to approve/verify it. I can continue without approval but then he doesn't have access to passwords and other settings. Once logged in I have tried to approve it again but still get stuck on the same screen of waiting for another device to approve. I'm kind of at a loss. Most recommendations I've read have to do with what sounds like going through the first process, but I can't figure out why it's asking twice, and why the second one isn't triggering the same approval option as the first.