We use SSL certificates, so that your subdomain of your WEBKiosk is secure. Your readers will see that the subdomain is secure.
You can select this option when you enter (or edit) a domain for your WEBKiosk.
Afterwards your readers will see that your Subdomain is secure:
If you are using CAA as in your domain, please make sure that you allow "Let's Encrypt" (https://letsencrypt.org/) to issue certificates with your domain name.
If this is not set, we can not encrypt your domain and create a certificate. So we can not make your subdomain secure. Your WEBKiosk will still work, but it will not be shown as secure.