The customer authorization (provided in the link you clicked) is out of date, and does not entitle you to use the Blended Threat service.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-trade-mark-law-after-brexit?utm_source=2b8f2b2c-d1b7-496d-84ef-3660daa62d8e&utm_medium=email&utm_campaign=govuk-notifications&utm_content=immediate