downloadStreamFromServer

   private async Task<MemoryStream> DownloadInvoiceFromFileServer(string invoiceInfoInvoiceId, string invoiceInfoFileExtension)
        {
            string path = AppSettingsConstants.FileServerEndPoint + $"/{invoiceInfoInvoiceId}.{invoiceInfoFileExtension}";
            var memoryStream = new MemoryStream();
            using (var fileStream = new FileStream(path, FileMode.Open))
            {
                byte[] buffer = new byte[1024];
                int byteRead;
                while ((byteRead = fileStream.Read(buffer, 0, buffer.Length)) > 0)
                {
                    await memoryStream.WriteAsync(buffer, 0, byteRead);
                }
            }

            memoryStream.Position = 0;
            return memoryStream;
        }