DocuSign document blank after request and save - docusignapi

Question

After requesting a document via the DocuSign api and writing it to the file system it appears blank after opening it. The docs say it returns a "PDF File" and the response body is returned as below.
const doc =
await rp.get(`${apiBaseUrl}/${BASE_URI_SUFFIX}/accounts/${accountId}/envelopes/${envelopeId}/documents/${document.documentId}`,
{auth: { bearer: token }}
);
fs.writeFile(document.name, new Buffer(doc, "binary"), function(err) {
if (err) throw err;
console.log('Saved!');
});
Response body:
{
"documents": [
{
"name": "Name of doc.docx",
"content": "%PDF-1.5\n%\ufffd\ufffd\ufffd\ufffd\n%Writing objects...\n4 0 obj\n<<\n/Type /Page\n/Resources 5 0 R\n/Parent 3 0 R\n/MediaBox [0 0 612 792 ]\n/Contents [6 0 R 7 0 R 8 0 R 9 0 R 10 0 R ]\n/Group <<\n/Type /Group\n/S /Transparency\n/CS /DeviceRGB\n>>\n/Tabs /S\n/StructParents 0\n>>\nendobj\n5 0 obj\n<<\n/Font <<\n/F1 11 0 R\n/F2 12 0 R\n/F3 13 0 R\n>>\n/ExtGState <<\n/GS7 14 0 R\n/GS8 15 0 R\n>>\n/ProcSet [/PDF /Text ...
}
]}
Screenshot of document:

Answer 1

The EnvelopeDocuments::get API method returns the PDF itself, not an object as you are showing.
For a working example of the method, see example 7, part of the Node.js set of examples.
Added
Also, the fs.writeFile call supports writing from a string source. I'd try:
fs.writeFile(document.name, doc, {encoding: "binary"},
function(err) {
if (err) throw err;
console.log('Saved!');
});
Incorrect encoding
Your question shows the pdf's content as a string with the control characters encoded as unicode strings:
"%PDF-1.5\n%\ufffd\ufffd\ufffd\ufffd\n%Writing objects...
but this is not correct. The beginning of a PDF file includes binary characters that are not displayable except in a hex editor. This is what you should see at the top of a PDF:
Note the 10th character. It is hex c4. In your string, the equivalent character has been encoded as \ufffd (it is ok that they aren't the same character, they are two different PDFs). The fact that the character has been encoded is your problem.
Solutions
Convince the requests library and the fs.WriteFile methods to not encode the data. Or to decode it as needed. See this solution for the requests library.
Or use the DocuSign Node.js SDK as I show in the example code referenced above.