curl --request GET \
  --url https://api.example.com/signature/by-external-id/{externalId}

{
  "signatureRequests": [
    {
      "metadata": [
        {
          "key": "<string>",
          "value": "<string>"
        }
      ],
      "id": "<string>",
      "name": "<string>",
      "deliveryMode": "EMAIL",
      "externalId": "<string>",
      "signers": [
        {
          "customerId": "<string>",
          "firstName": "<string>",
          "lastName": "<string>",
          "email": "<string>",
          "yousignId": "<string>"
        }
      ],
      "documents": [
        {
          "id": "<string>",
          "type": "ATTACHMENT",
          "anchor": {
            "page": {},
            "x": 123,
            "y": 123,
            "height": 123,
            "width": 123
          },
          "mentions": [
            "<string>"
          ],
          "texts": [
            "<string>"
          ],
          "checkboxes": [
            "<string>"
          ]
        }
      ],
      "status": "PENDING",
      "signedAt": "2023-11-07T05:31:56Z",
      "reminderSettings": {
        "delay": 1,
        "maxAttempts": 5.5
      }
    }
  ]
}