The login link and the admin details, work.
First, you will have to register the test domain link as the staging site for the license. http://box5177.temp.domains/~milesco6/
Please note that you can register a staging and production link for each license. Since you current have a test/temporarily link, you may register it as the staging link.
Once registered with the license, you could use the license key to validate the test site.
I have gone ahead and did the steps above and validated the test site for you.
Kindly see you licenses page that was previously linked in this thread so that you could see where there license was registered with the domain.
Hope this helps.