Cloudflare DNS doesn’t allow zone transfers. However, you can download the entire DNS zone file through the API. Maybe Virtualmin will let you import it.
Keep in mind that these records will be the origin IP addresses, and not the public IP address Cloudflare shows for your domain. Also, you can only have Cloudflare name servers assigned to your domain. So if you’re trying to use this as a failover, you’ll need that extra step to change name servers at your registry.