Keychain

See >>> If iCloud Keychain won't turn on or sync - Apple Support

mlucassen wrote:

Hi i'm new to iphone, i have the iphone 14 pro and the 9th generation ipad. The keychain toggle will not turn on on my ipad, the passwords aren't syncing to both devices

I assume that the toggle does turn on on your iPhone and that you are using two factor authentication. If that’s the case, try restart your iPad and then try setting up Keychain again.

Restart your iPad - Apple Support