How do I approve my iPhone when prompted to from another device signed in to my iCloud?

See if anything here helps. 

Verification code - how to get one and sign in with two-factor authentication.   

i dont remember the passcode that you're made to setup when you initially start up your device in order to gain access to my saved passwords and other things that are end to end encrypted. its giving me 2 options, approve device from another device logged into icloud or reset end to end encryption. anyone know what i can do??

See if anything here helps. 

Verification code - how to get one and sign in with two-factor authentication.   

I'm signed in to another device but dont know what to do next to

approve another I phone

See my post above your post.

How do I approve my newdevice?

i have no idea how to do this my phone have been loading for 20 min. now telling me waiting for approval.