I was introducing MIT App Inventor to my students and we were trying to set up accounts, however my students said what when they tried to create an account (both with their school email addresses and personal email addresses) they didn't receive a code or link. I have also tried creating a new account with another email address and still have not received a code or link.
Is this affecting all students? If they are using a school email, it's possible that the school district is blocking email from outside the district, in which case they students won't be able to receive the create password email.
We had a problem on our side (MIT), which I just fixed. Unfortunately, some of your students may now receive e-mail messages (from earlier) with links or codes that have timed out. But new requests should work fine.