You can verify yourself as the owner of the links in your profile metadata. For that, the linked website must contain a link back to your Mastodon profile. The link back must have a rel=“me” attribute. The text content of the link does not matter. Here is an example:
Re: Verification - Mastodon
Hello, I have never seen such a request for verification in this manner, you would have to contact them for help in this case. If a met tag is all that is needed, you can use our built in meta tag editor in the admincp to do so though.