The customer authorization (provided in the link you clicked) is out of date, and does not entitle you to use the Blended Threat service.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/export-live-animals-special-rules?utm_source=877f44eb-8ea7-48ae-bdef-1c7dcae7d033&utm_medium=email&utm_campaign=govuk-notifications&utm_content=immediate