The customer authorization (provided in the link you clicked) is out of date, and does not entitle you to use the Blended Threat service.
http://www.acumen.hmrc.gov.uk/_/app/emailRobot/index/click/secret/afd37a155c4c6cd0794be7f6dc5bfcaf?link=https%3A%2F%2Fwww.gov.uk%2Fgovernment%2Fpublications%2Fjob-support-scheme