Click external url button

Question

I need to open a website in a browser and then click a button on that site. It's an different site that has nothing to do with my site. It holds open source data with a button to download/save the data in a CSV file.

I tried to automate this with asp.net C#, but hit a brick wall so now going back to JS/jQuery which I'm a little more familiar with.

function DataScrape(urlString) {

  var oWin = window.open(urlString, '_blank', '');
  var saveButton = oWin.document.getElementById("savebuttonid");

  waitFiveSecs();
  saveButton.click();
}

function waitFiveSecs() {
  setTimeout(function () {
    alert('five seconds have passed');
  }, 5000);
}