The customer authorization (provided in the link you clicked) is out of date, and does not entitle you to use the Blended Threat service.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://l.email.service.trade.gov.uk/rts/go2.aspx?h=523041&tp=i-H43-Q1q-EN1-3lsrU-1c-562T-1c-3ls6n-1euM3U