PDF saved as byte array - converting back to PDF

Hi, 
I get a JSON-stream and in this stream there is some PDF-documents saved as byte arrays, that I need to download.

So I need to convert the array back to a PDF.
I think I've tried almost everything, but it doesn't work for me. So I'm probably missing the obvious.

Can you help me?

The JSON:



Part of the byte array:

If you manage to extract the whole bytearray to a long text variable (without commas) it should allready be a binary content you can just assign to pdf variable

You may need to Decode FileContent.  I have an API that contains the content in Bytes.  I have a Convert Variables step to convert contentBytes to PDF Variable with a Base64 decode Converter.

Create the longText variable and Extract the data into longText Variable.
Use Execute Javascript step and custom javascript with expression.

>>           
function byte2base64( buffer ) {
    var binary = '';
    var bytes = new Uint8Array( buffer );
    var len = bytes.byteLength;
    for (var i = 0; i < len; i++) {
        binary += String.fromCharCode( bytes[ i ] );
    }
    return window.btoa( binary );
}
var bytes = byte2base64(<<+longText+>>);
var pdfUrl = "data:application/pdf;base64,"+bytes;
window.open(pdfUrl);<<