Help fixing Zip Folder download error

Controller

   public function bulkDownload(BulkDownloadMediaRequest $request)
{
    $medias = [];
    foreach ($request->media as $id)
    {
        //object of media
        $media =  $this->medias->find($id);
        $medias[] = $media;

      //if i want cd url for a media then I can get by doing  $media->getUrl()
    }
    return MediaStream::create('eventName.zip')->addMedia($medias);

}

ajax call

  var media = this.selectedItemIds;
                $.ajax({
                    type: 'GET',
                    url: '{{ route("myroute.bulkDownload") }}',
                    contentType: 'application/json; application/octet-stream',
                    responseType: 'blob',
                    data: {media:media},
                    success: function (res, status, xhr) {
                        var headers = xhr.getResponseHeader('content-disposition');
                        var fileName = headers.toString().split('=')[1].toString().replace(/\"/g, '');
                        var blob = new Blob([res]);
                        var link = document.createElement('a');
                        link.href = window.URL.createObjectURL(blob);
                        link.download = fileName;
                        link.click();
                    }
                })

When I try to open downloaded zip folder it gives me `Unable to expand 'eventName.zip. into "downloads". (Error 79 - Inappropriate file type or format.)