The replacement tag $CALL_STRATEGY_LINK$ can be used in the appointment notification templates (confirmations and reminders) that you create, edit and manage in CALENDAR TAB > Notification Templates. The replacement tag can be inserted from the drop-down list of Replacement Tags in the editor menu. When the appointment confirmation or reminder is sent, the replacement tag will be converted into a link to the form that you assign as call strategy form for a specific appointment type.
Important: You also need to make sure the contacts to who the appointment reminder is sent have permissions for that specific form (in WEBSITE TAB > Forms > specific form in edit mode > "Form permissions" tab). If a client does not have permission for the respective form, the replacement tag $CALL_STRATEGY_LINK$ will not generate the link to the form in the reminder sent to the client.