docs
DNS Setting
Domain bought on Other Provider

if you have already registered domain with other provider then comment out

    this.hostedZone = route53.HostedZone.fromLookup(this, 'HostedZone', {
      domainName: domainName,
    });

and uncomment

   this.hostedZone = new route53.PublicHostedZone(this, 'HostedZone', {
       zoneName: domainName,
    });

so it can create a new host zone