The website is https://caption-manager-docs.netlify.app/
The error message is “A DNS zone for this domain already exists under a different account”.
I already saw the support guide.
I’m trying to verify the domain “caption-manager-docs.netlify.app”. I don’t have any other accounts (and neither my organization), so I don’t see how a DNS zone can already exist.
What should I do?
A DNS zone already exists for netlify.app because that domain is managed by Netlify for the users of the service.
Where/Why are you trying to verify this domain?
Thanks for answering!
I’m developing a Google Docs Add-On and I’m hosting the docs, privacy policy and terms of service on the https://caption-manager-docs.netlify.app/ website. I need to verify the domain as a requirement of the Google’s OAuth consent screen. See here:
https://support.google.com/a/topic/1409901?authuser=0
I wish I didn’t have to buy a domain to do this 
This documentation is specific to using a domain with Google Workspace, with the apps *(e.g. Gmail.) If this is the case, then there is no option than to have your own domain.
If you’re making money (or planning to) then surely this is a small price to pay.
However, if it is only the docs site that you need to verify, is there no option to use a HTML tag (as is the case with Search Console?)