Cannot "Approve This iPad" from my iMac

Trying to approve my iPad from my iMac (Early 2009—24"—2.66 GHZ Dual Core—El Capitan 10.11.6)

I signed onto iCloud, a verification number appeared.

I entered it on my iPad

Now iPad displays a spinning icon with "Waiting for approval..."

Approval never comes.

Have been down this road before; I hate 2-factor authorization with its obscure on-screen instructions that simply do not work. I wish so much I had never started it. Can't turn it off, and I have spent hours and hours trying to do what seems impossible. Maybe it is, but I wish it would say so instead of "Waiting for approval..." for hours.

I've been a loyal Apple user since the old Apple II green screen (CAPITAL letters not included). I've owned numerous iMacs. It is so disappointing to keep finding these un-Applelike issues. If I wanted to struggle with a PC-mentality, I could have bought one for a lot less. Sigh. You're my last hope.