How do I backup a iPhone that is not mine
Have a work phone I need to backup so I can have this information to transfer to a new phone
Have a work phone I need to backup so I can have this information to transfer to a new phone
Follow the steps in the support document you posted from.
Finder will backup the connected iPhone to the Mac whether its signed in to your Apple ID or not.
The backup will be independent and not get mixed up with other backups you may have on your computer.
How do I backup a iPhone that is not mine