The customer authorization (provided in the link you clicked) is out of date, and does not entitle you to use the Blended Threat service.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/brexit-guidance-for-eu-students-in-the-uk?utm_source=d22bf2fd-b7a9-4d30-98bd-917e52930ad7&utm_medium=email&utm_campaign=govuk-notifications&utm_content=immediate