post
https://api.ext-sandbox.fourthline.com/v1/signatures//authorize
When the signature status changes to user_consent_required and after making the Get signature details request, use this endpoint to confirm that the client has approved the documents to sign and accepted the QTSP legal conditions. 
Important:
• Before using this endpoint, see the integration guide.
• signatureId and workflowId are string identifiers that can be used interchangeably.
Tip: When testing this endpoint, you must use a real ID document with an MRZ or VIZ.