This is super, duper awkward. Struggled mightily with this process because it didn't follow the posts. In the end, had to start with signing out as noted. So, I sign out, sign back in, get a code. Then I go back in to follow these silly instructions but now it DOES ask me for a 6 digit code with a box to enter it in. So I entered it - but it STILL doesn't work. Now I go back again and sign out and sign in with the code tacked onto the end of the password and select not to remember for iTunes purchases. This FINALLY worked. What is extremely irritating about Apple in general is the assumption is it is intuitive. Please remove the rose colored Apple glasses. This process stinks. This is a classic example that you can't see how frustrating it is to work with your products at times. Couldn't there have been a note added to the screen for the sign up of the app? Anything to guide you to this online forum prior to spending ridiculous amounts of time chasing codes on various phones, ipads, etc?