It's not possible to validate an ACM public certificate using a domain record in a Route 53 private hosted zone.
When you request an ACM public certificate using DNS validation, ACM provides a CNAME record that you must add to your DNS configuration to validate your ownership of the domain. Because anyone can create a private DNS zone and put records on it under any domain name, being able to make a change in a private DNS zone doesn't prove public ownership of the domain.
For more information on DNS validation, see DNS validation in the ACM user guide.
Route 53 domain cname record without hosted zoneAccepted Answerasked a year ago
ACM certificate validation pending with Route 53 hosted zone with parent domain in other DNS serviceAccepted Answerasked 2 months ago
ACM certificate DNS validation does not validate my certificateasked 3 months ago
AWS Route 53 A record shows up as CNAME in public DNS lookupsasked 4 months ago
New ACM Cert pending validation after creation of Route53 CNAME recordasked 7 months ago
[bug] aws provisioned acm certificate validation time out in route53 registered domainasked a month ago
Can you validate an ACM public certificate using a domain record in a Route 53 private hosted zone?Accepted Answerasked 5 years ago
ACM Certificate issued for an private hosted zone, status stuck on pending validationasked a month ago
Trying to Validate domain ownership in ACM , stuck at pending after CNAM createdasked 8 months ago
ACM certificate won't validate for newly registered domain in Route53asked 5 months ago