Cannot sign-up for forum.gitlab.com

I tried to create an account for forum.gitlab.com using all available options (e-mail, GitHub.com, GitLab.com).

The sign-up with e-mail authentication failed because I did not received the e-mail after 20+ minutes. Yes, I checked the "Spam" folder and I pressed the "Resend" button several times.

Sign-up with GitHub and GitLab accounts fail with the following error message:

The line

if the error condition persists, you can provide additional detail, including steps to reproduce the error, by posting a discussion topic in the site's feedback category.

is hilarious because it asks me to post a topic in a forum which I cannot access.

Please fix the issue and tell me what authentication option (e-mail, GitHub, GitLab) works for creating an account at forum.gitlab.com.