Hello,
Thank you for contacting Rank Math and sorry for any inconvenience that might have been caused due to that.
This error suggests that the service account is not listed as Owner for the site in Search Console. You can fix this by following these steps:
This error suggests that the service account is not listed as Owner for the site in Search Console. You can fix this by following these steps:

On the next page, add the service account as an owner with the button:

Then, head back to the Search Console and refresh to confirm that the service account has been added correctly.
I hope this resolves your issue.
Hi,
I am following those steps, but when I click Manage Property Owners, I don’t have an Add Owner option. I have only Add Property, but I cannot enter email there, only web URL.
Thanks
Hi,
right now I saw, when I click on my property (my website URL), I have an Add owner option there. Should I add a service account there?
Hello,
Yes, that would be correct. You need to enter your email as a property owner and get it to verify.
I hope this resolves your issue.