Javascript to connect to SharePoint Online from eforms

using something like this for on premise and this works.

But when I try to use the same JS to connect to SPOnline getting 403 error message. anything obvious I am missing here ?

form url start with : https://office365app.nxone.com/

host url is SPOnline url.

function GettemAttachments() {
var ItemID = document.getElementById("DS_ID").value;

    $.ajax
    ({
        url:"_api/web/lists/GetByTitle('List Name')/items("+ItemID+")/AttachmentFiles",
        method: "GET",
        headers:
           {
             "Accept": "application/json;odata=verbose",
             "content-type": "application/json;odata=verbose",
             "X-RequestDigest":$("#_REQUESTDIGEST").val()
           },
        success: function (data, status, xhr) {
             var dataresults = data.d.results;
          var text = "";
          var aURL = "
            for (var i = 0; i < dataresults.length; i++) {
                alert(dataresults[i]["FileName"]);
                var fileName = dataresults[i]["FileName"];
             //alert(dataresults[i]["ServerRelativeUrl"]);
              text += aURL+ItemID+"/"+fileName+"'>"+fileName+"<br><br>";
              
             }
           document.getElementById("AttachmentsHTMLControl").innerHTML = text;
        },
        error: function (xhr, status, error) {
            console.log("Failed");
        }
    });

}