Need help with verifying ownership for netlify domain

Hi, I am reaching out because of the DNS issue with the site I created with netlify. I was trying to enable my website homepage to show up on Google search. However, I cannot find DNS Configuration.

The post here says the settings can be found under ‘Domain Name’, but when I try to add my domain, I got error “A DNS zone for this domain already exists under a different account”. Could you help me with the domain verification? My netlify site name:

Or, where else can I find the DNS configuration?

What’s the domain you’re trying to add?

But the ultimate goal is to make my site visible in Google search. What do I need to do with that?

That’s not the domain, that’s the site name. What custom domain are you trying to add that’s giving you the error: