.cs

 public async Task<IActionResult> OnPostAsync(string opt, string value)
        {
            ProcessStartInfo start = new ProcessStartInfo();
            start.FileName = "python/python-3.8.0-embed-amd64/python.exe";
            start.Verb = "runas";
            start.Arguments = $"python/backend.py {opt} {value}";
            start.UseShellExecute = false;
            start.RedirectStandardOutput = true;
            using (Process process = Process.Start(start))
            {
                using (System.IO.StreamReader reader = process.StandardOutput)
                {
                    dynamic result = JObject.Parse(reader.ReadToEnd());
                    
                    var stream =  new FileStream(result.path, FileMode.Open);
                    var fileName = "document.pdf";
                    var mimeType = "application/pdf";
                    if (result.status == "Success")
                    {
                        stream =
                      return new FileStreamResult(stream, mimeType)
                      {
                          FileDownloadName = fileName;
                      };
                    }
                    else if (result.status == "ErrorDNE")
                    {
                    }
                    else if (result.status == "ErrorMRE")
                    {

                    }
                    Console.WriteLine(result);
                }

            }

        }