The customer authorization (provided in the link you clicked) is out of date, and does not entitle you to use the Blended Threat service.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://click.email.tfl.gov.uk/?qs=51ade3925fe51eb8ccc0f860afe5fa4891284ad0a352fe70eabc1aea7ea9d9d1b39f312faf3d0e114acf1064a5b8946b4d5d642d04f26908