The customer authorization (provided in the link you clicked) is out of date, and does not entitle you to use the Blended Threat service.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/horizon-2020-funding-after-brexit?utm_source=d2e7e9b4-6b50-49e1-8ef0-c7d17ed60c7e&utm_medium=email&utm_campaign=govuk-notifications&utm_content=immediate