Here are a few steps you can take to troubleshoot the issue of not receiving your authorization code.
1. Check your spam folder for the message.
2. Add firstname.lastname@example.org to your safe list then try resending the email.
3. If step 2 did not resolve your issue, try updating ONLY the admin email to another email address.
4. If step 3 did not resolve your issue, export the domain list from the domain manager to include the auth code.