Travel on the Harbour Bridge / Tunnel is operated by Transport for NSW. You can only pay for this travel using Linkt up to 72 hours after you’ve travelled. As it’s been more than 72 hours, you’ll most likely receive a toll notice from Transport for NSW for payment.
Search for your Transport for NSW toll notice
However, you can pay for all future travel via Linkt, including future trips on the Harbour Bridge / Tunnel.