Sign in Issues

My students try to sign into their adobe accounts and it asks them to verify their email address. They input the code that is sent to them and it says error wrong code. I have them resend the code and it does the same thing. It only does this to a handful of my students and the rest of them have no probelm at all. Then it gives them a error that says try again later. We try it again the next day and the same probelm persists. I've tried contacting adobe themselves and have not heard back nor can I actually find someone to help me from adobe. Any help would be aprreciated.