This can happen due to DNS caching; if you had tried to view the domain before it was registered, your DNS provider (usually your ISP) may have saved the DNS result for that page, which points to our placeholder "Does Not Exist" server. Your local PC may have also done this; you can often fix it by opening a Windows command prompt and running "ipconfig /flushdns" without the quotes, but if your DNS provider cached the result it may take 24-72 hours (usually not more than 24) for the old result to "expire" and begin pointing to the correct server.
You also weren't able to re-create a new account with the old domain as you had submitted an account cancellation, but to give time to revert that decision, that takes 72 hours. You should be able to login and remove the cancellation request if you'd like to try the DNS clearing step above, to see if that makes the page load before your DNS provider "expires" the saved record they have.