2-Step verification is prime feature when it comes to the eMail security. You have to add one or two mobile numbers in your account and whenever you log into that account you get an OTP and notification. Apple ID login works the same way it is very secured. Visit Apple ID Support Number to follow the steps.
Some factors which may be responsible for the problem might be: App or iOS is infected by bug, iOS device is incompatible, Poor network connection, Memory issue or Faulty download . For more information click iPhone Support Number.