Thanks for reaching out.
Typically when this error occurs when attempting to make a domain purchase it is due to the system not detecting the address used as being accurate. I recommend validating your address using Google and copy/pasting that exact address into the appropriate fields and trying again. I would also suggest that you make sure that the zip code is added does not have any additional characters or spaces.
Let me know if that does the trick, looking forward to your response.
I have tried copying the address from Google but it doesn't work, and it seems there is neither zip code or postal code field available to fill in.
Thanks for the quick reply.
In this case, we will need to take a closer look into the store to gather a bit more context. Since we cannot authenticate you over our public forums, we will need you to login to your store using our Contact Us page. This will allow us to securely verify you as the store owner before discussing the issue with a Support Advisor.
Let me know if you have any trouble.