unable to download zip file

I have a table with list of orders where each order have their own airway bill note. The airway note is actually an external URL(given by API response) where if I click on it, it will present a download box to user to download and save the file. I now wanted to allow the user to select multiple consignment notes so they can download in bulk.

I thought of having a checkbox for user to select and then in my controller, create a zip file and add those airway to it and return it to the user to download. Currently, I am using this zip package by zanysoft/laravel-zip. I am not too sure if it allows to add external URL inside the zip file.

Here is my Ajax request:

  $('.download_bulk').on('click', function(e) {
            e.preventDefault();
            let allVals = [];
            $(".subChkOrder:checked").each(function() {
                allVals.push($(this).attr('data-id'));
            });
            if( allVals.length <= 1 ) {
                alert("Please select more than 1 row.");
            } else {            
                    let join_selected_values = allVals.join(",");
                    $.ajax({
                        url:"{{route('order.print.bulk')}}",
                        type: 'POST',
                        headers: {'X-CSRF-TOKEN': $('meta[name="csrf-token"]').attr('content')},
                        data: 'ids='+join_selected_values,
                        success: function (data) {
                            //window.location = data;
                            if(data['success']) {
                               alert(data['data']);
                               
                            } else if (data['error']) {
                                alert(data['error']);
                            } else {
                                alert('Whoops Something went wrong!!');
                            }
                        },
                        error: function (data) {
                            alert(data.responseText);
                        }
                    });
                
            }
        });

And in my controller:

public function printBulkConsignment(Request $request){
        $ids = $request->ids;
       
        $datas = Order::whereIn('id', explode(',', $ids))->get();
        $consignments= array();

        foreach($datas as $data){
            $consignments[] = '"'.$data->awb_id_link.'"';
        }

        $zip = Zip::create('file.zip');

        $zip->add($consignments);

        $zip->close();

        $data = json_encode($zip);
       
        return response()->download($zip);
        //return response()->json(['success' => 'Print bulk success', 'data' =>$data]);
    }

The awb_id_link is external URL like "https:..../external_url/path_to_download" Upon submitting the request, the alert keeps showing an error:

message : Object of class Zanysoft\Zip could not be converted to string

I am not too sure why the user is unable to download the zip, how do I solve it?