iPhone 6s setup: the dialog to enter zip code is missing the return key. The only choice is to cancel (which surprisingly works for entering the zip). The return key is present on the iPad Air 2.
Strange. Can you verify the version of iOS on both devices?
9.3.2 (13F69) on both devices.
First photo is iPhone. Second photo is iPad.
Note the return key on the iPad that one can press after zip code is entered. As for the iPhone, it is not obvious what to do after entering the zip code. You should add an OK button to the dialog.
This is fixed in 7.12.38 (as the release notes state).