Download file from signed S3 url on click

I have a signed Amazon S3 URL which points to a PDF file in a bucket

I want to download this file, not redirect/display it, when a button is clicked.

I had figured something like this

Router.route('download', {
  path: '/d/:signedURL',
  onAfterAction: function() {
    var req = this.request;
    var res = this.response;

    res.setHeader('Content-disposition', 'attachment; filename=' + this.params.signedURL);

    console.log(req, res);


  }
}, {where: 'server'});

But can't get it to work, any advice?