In the Android 5 login flow you are seeing different screens because the Twitter for Android app isn’t installed and you are being redirected to the web login.
In the Android 6 login flow it looks like your version of Twitter for Android is out-of-date. Only Twitter for Android v6.32 and newer can grant permissions for all scopes of the Twitter API, including permission to request email addresses, and direct messaging. Older versions of Twitter for Android do not have the ability to grant these extended permissions.
Also we recently released Twitter Kit 3.0 which removes the requirement to show the “Share your email address” screen. See: https://dev.twitter.com/twitterkit/android/upgrading
