I can’t download the pdf file with FileStreamResult when I call it from ajax

I am trying to call my FileStream Result function from an ajax, the question is that it is calling the method and it does everything inside, I checked this with a breakpoint, but at the end it is not downloading the pdf I want. Before it was downloading and it was calling it from
like this: “using (Html.BeginForm("EmisionAllLabel", "WareHouseReceipt", FormMethod.Post))“. But now I need to do it from an ajax but it doesn’t work for me. Maybe it’s because I’m missing something but I don’t have much experience with ajax regarding this and I can’t identify the problem. I appreciate your comments.
Attached are the codes used:

    $('#btnValidarEmision').on("click", function () {

        let emisionguia = $('#guiaAerea').val();
        $.ajax({
            url: "/WareHouseReceipt/" + "EmisionEtiqueta",
            type: "POST",
            data: { "guiaAerea": emisionguia },
            success: function (saved) {

            },
            error: function () {
                console.log("Error");
            }
        });
    });

FileStreamResult

public FileStreamResult EmisionEtiqueta(string guiaAerea)
{

    IList<ICriterion> criterionlist = new List<ICriterion>();
    criterionlist.Add(Expression.Eq("Econtainer", true));
    criterionlist.Add(Expression.Eq("StatusId", 1));
    criterionlist.Add(Expression.Eq("Emision", false));
    IList<VwWareHouseReceipt> etiquetas = vwWarehouseReceiptDao.findByCriteria(criterionlist);


    //mem buffer
    MemoryStream ms = new MemoryStream();



    //the document
    Document document = new Document(new Rectangle(float.Parse("289.50"), 370, 0, 0));

    BaseFont bf2 = BaseFont.CreateFont(BaseFont.TIMES_ROMAN, BaseFont.CP1252, BaseFont.NOT_EMBEDDED);

    BaseFont helveticanormal = BaseFont.CreateFont(BaseFont.HELVETICA, BaseFont.CP1252, true);
    BaseFont helveticanegrita = BaseFont.CreateFont(BaseFont.HELVETICA_BOLD, BaseFont.CP1252, true);

    //create the fonts
    BaseFont timesNormal = BaseFont.CreateFont(BaseFont.TIMES_ROMAN,
                                               BaseFont.CP1252,
                                               BaseFont.NOT_EMBEDDED);

    Font fontSmall = new Font(timesNormal, 7, Font.NORMAL);

    Font fontNormal = new Font(timesNormal, 9, Font.NORMAL);

    Font fontH1 = new Font(timesNormal, 16, Font.NORMAL);

    //the writer
    PdfWriter writer = PdfWriter.GetInstance(document, ms);//fs);

    // step 3: we open the document
    document.Open();

    for (int i = 0; i < etiquetas.Count; i++) { 
    

    }
    document.Close();

    //close the document
    // document.PageSize = PageSize.HALFLETTER;
    //document.PageSize = PageSize.

    //prepare output stream
    Response.ContentType = "application/pdf";
    Response.AddHeader("content-disposition", "attachment;filename=EtiquetasEmisionEcont" + guiaAerea + ".pdf");
    Response.Buffer = true;
    Response.Clear();
    Response.OutputStream.Write(ms.GetBuffer(), 0, ms.GetBuffer().Length);
    Response.OutputStream.Flush();
    Response.End();

    return new FileStreamResult(Response.OutputStream, "application/pdf");

Note: I deleted the “for” so that there would not be too much text.