Why is my download failing for most recent csv file?

Question

I am attempting to download the most recently upload csv file. The app is built with express, html, and javascript, just FYI. I have an anchor tag in my index.html file and inside of my app.js file's success callback I am attempting to download the appropriate data. However, I am coming up with Failed - No File. Below you will find my index.html and app.js relevant code:

index.html:

<a href="csv.txt" id="download" download>Download CSV</a>

app.js:

$('form').on('submit', function (event) {
  event.preventDefault();

  var newInfo = document.getElementById('info').files[0];

  var formData = new FormData();
  formData.append("jsonfile", newInfo);

  $.ajax({
    type: 'POST',
    url: '/upload_json',
    data: formData,
    contentType: false,
    processData: false,
    success: function (data) {
      console.log('DATA: ', data);
      $('#csv').html(data);
      $("a").attr("href", data)
    },
    error: function(err) {
      console.log('ERR: ', err.responseText);
    }
  })

});