Verification code error for Apple developer account creation

I already have a paid Apple Developer account. However, one of my clients has just created a user with admin role in their Apple Developer account and sent the invitation to one of my other emails (the one that is NOT used for my own paid Apple Developer account). Upon receiving the email, I clicked on the Accept Invitation link and got redirected to the account creation page. After putting in my phone numbers and different things, I got a message saying "Verification codes can’t be sent to this phone number at this time. Please try again later." I have tried it multiple times yesterday and today (the total would be no fewer than ten times throughout different times of the day) and the same error message always comes up. Does anyone know how I can bypass this screen and create an account please?

[Re-Titled by Moderator]