Connect Route53 to CNAME outside of AWS

I am trying to create a record on my Route 53's Hosted zones. I selected "CNAME – Routes traffic to another domain name and to some AWS resources" as the Record Type and typed the domain, that runs my web application which is running onpremise outside of AWS, in the Value text field. Routing Policy is set to simple routing. When I click Create Record, I get this error:

Error occurred
Bad request.
(InvalidChangeBatch 400: RRSet of type CNAME with DNS name mydomain.it. is not permitted at apex in zone mydomain.it.)

Is it because the domain I typed in the value is not a domain reachable to AWS? I read that In Route53 Alias is only allowed when you have to point to AWS resources, but in my case the Alias field is not selected. Note that if I set a subdomain it works.

Thanks!