In this case, be sure to write to our Customer Service. It is possible to obtain an alternative method to confirm your domain, but we need to know about the need.
Such alternative methods depend on the domain you want to protect with the SSL certificate. As soon as we know you need other ways to validate your domain, we will send you this policy.
Lest you be surprised, the most common ways are
adding a file with specific content in a specific location of the website
adding a TXT record with a specific value to the domain