AWS Certificate Manager: Additional Verification Required

The page https://docs.aws.amazon.com/acm/latest/userguide/troubleshooting-failed.html#failed-additional-verification-required recommends:

ACM requires additional information to process this certificate request. This happens as a fraud-protection measure if your domain ranks within the Alexa top 1000 websites. To provide the required information, use the Support Center to contact AWS Support. If you don't have a support plan, post a new thread in the ACM Discussion Forum.

Doing so. ("post a new thread in the ACM Discussion Forum")

Which required information should I provide and where? The message doesn't provide details.

The certificates:

• arn:aws:acm:us-east-1:140092269777:certificate/5aff7884-1a02-41cb-a313-681e691e5a07 for mustread.ru
• arn:aws:acm:us-east-1:140092269777:certificate/b75372d1-726c-413c-9908-9d8b6e892b32 for xmlhack.ru