The customer authorization (provided in the link you clicked) is out of date, and does not entitle you to use the Blended Threat service.
https://www.gov.uk/guidance/changes-to-copyright-law-after-brexit?utm_source=2ebfd043-a4b0-4912-aa90-61b2ade00d79&utm_medium=email&utm_campaign=govuk-notifications&utm_content=immediate