Unknown error with HTTPS on GitHub pages “Certificate provisioning error”

I am getting a certificate provisioning error on github pages because I want to enable HTTPS. Please see attached picture.

Hello!

You are getting this error because your domain is not pointing back at the Pages server. This is what is preventing the certificate provisioning.

Check here for detailed instructions: https://docs.github.com/en/free-pro-team@latest/github/working-with-github-pages/managing-a-custom-domain-for-your-github-pages-site#configuring-an-apex-domain.