This is an example of how to set up AFS on Freshdesk, to trigger invitations when a certain action related to the tickets is completed.

Admin -> Automations -> Ticket Updates -> New Rule

When an action performed by... "Agent or Requester"

Involves any of these events: "Status is changed" from "Any Status" to "Resolved"
On tickets with these properties: Leave the default here

Perform these actions: "Forward" To "Your Trustpilot BCC address"

Description should be: 

<script type="application/json+trustpilot">
{
"recipientName": "{{ticket.contact.firstname}}",
"recipientEmail": "{{ticket.contact.email}}",
"referenceId": "{{ticket.id}}"
}
</script>