The Authorize token is not enabled by default in your instance as it is an optional feature. In order to have this feature enabled please notify your point of contact at Flinks.
It is important to clarify that the Authorize token is an optional security layer. By activating it, you will need to generate and provide an Authorize token every time a new connection is intended, regardless of it being through Flinks Connect or through the Authorize endpoint, such as described here. Depending on the use case, it might add to the complexity of the integration and possibly interfere with further troubleshooting.