How can I download PDF files with HttpRequest

I have a problem, my program reads an ODT file and downloads the links inside it, these links correspond to PDF files available on an intranet. The problem is that as a result of the program, I don't have 128 pdf that are downloaded but I have 128 files (which correspond well in terms of name to what I am supposed to have) without extension, and which are all 18 kb of size.

My question is then the following: Why do I not have PDF files in output but files without extension as on the screenshot? Is it a redirect problem ? I also tried with DownloadFile method and i have the same result.

The System.Diagnostics.Process.Start(link); method works but I can't rename the files because the program only execute them and doesn't downloads them(the browser downloads them).

PS : i'm on .NET 3.5 and Visual Studio 2010

results of downloaded files ===> Here if the first link doesn't work : https://snipboard.io/nwcdM1.jpg

I expected the same names but with pdf extension and more than 18kb...

here is my code :

using System;
using System.IO;
using System.Net;
using System.Text;
using System.Text.RegularExpressions;
using ICSharpCode.SharpZipLib.Core;
using ICSharpCode.SharpZipLib.Zip;

namespace PrepareDocForExternalUse
{
    class Program
    {
        static void Main(string[] args)
        {
            // Prompts the user for the absolute path to an ODT file
            Console.WriteLine("Please enter the absolute path of an ODT file:");
            string odtFilePath = Console.ReadLine();

            // Read the contents of the ODT file
            byte[] content = File.ReadAllBytes(odtFilePath);
            MemoryStream ms = new MemoryStream();
            ms.Write(content, 0, content.Length);
            ZipFile zf = new ZipFile(ms);
            zf.UseZip64 = UseZip64.Off;
            zf.IsStreamOwner = false;
            ZipEntry entry = zf.GetEntry("content.xml");
            Stream s = zf.GetInputStream(entry);

            // Convert stream to string
            StreamReader reader = new StreamReader(s);
            string contentXml = reader.ReadToEnd();

            // Search for all links that start with "applnet.test.fr"
            string pattern = @"http://applnet\.test\.fr/GetContenu/Download\.aspx\?p1=.*?;p2=.*?;p5=.*?;p6=NOPUB";
            Regex regex = new Regex(pattern);
            MatchCollection matches = regex.Matches(contentXml);

            Directory.CreateDirectory(Path.GetDirectoryName(odtFilePath));

            // Process each link found
            foreach (Match match in matches)
            {
                string link = match.Value;
                string[] parts = link.Split(new string[] { "aspx?" }, StringSplitOptions.None);
                string queryString = parts[parts.Length - 1];


                // Download the corresponding intranet document
                string folderName = Path.GetFileNameWithoutExtension(odtFilePath);
                string subFolderName = "PJ - " + folderName;
                string fileName = queryString;
                string localFilePath = "C:/PiecesJointes/" + fileName;
                string onlineFilePath = "https://com.test.fr/files/test/test/" + queryString;

                HttpWebRequest request = (HttpWebRequest)WebRequest.Create(link);
                request.AllowAutoRedirect = false;
                request.Method = "GET";
                request.ContentType = "application/pdf";
                HttpWebResponse response = (HttpWebResponse)request.GetResponse();
                Stream stream = response.GetResponseStream();
                byte[] buffer = new byte[4096];
                int bytesRead = 0;
                FileStream fileStream = new FileStream(localFilePath, FileMode.Create);

                do
                {
                    bytesRead = stream.Read(buffer, 0, buffer.Length);
                    fileStream.Write(buffer, 0, bytesRead);
                } while (bytesRead > 0);

                fileStream.Close();
                response.Close();


                // Replace the link with the path of the downloaded document
                string newLink = localFilePath.Replace("\\", "/");
                contentXml = contentXml.Replace(link, onlineFilePath);
            }

            // Updates the content.xml in the initial ZIP file
            byte[] contentXmlBytes = System.Text.Encoding.UTF8.GetBytes(contentXml);
            ms = new MemoryStream();
            zf.BeginUpdate();

            // Add updated content to ZIP file
            ZipOutputStream zos = new ZipOutputStream(ms);
            zos.UseZip64 = UseZip64.Off;
            zos.IsStreamOwner = false;

            // Add entry for content.xml file
            zos.PutNextEntry(new ZipEntry(entry.Name));
            StreamUtils.Copy(new MemoryStream(contentXmlBytes), zos, new byte[4096]);

            // Processes each entry from the original ODT file
            foreach (ZipEntry origEntry in zf)
            {
                // Ignore the entry for the content.xml file because it has already been added
                if (origEntry.Name == entry.Name) continue;

                // Add entry to new ZIP file
                zos.PutNextEntry(new ZipEntry(origEntry.Name));
                StreamUtils.Copy(zf.GetInputStream(origEntry), zos, new byte[4096]);
            }

            zos.Close();

            // Finish updating the ZIP file
            zf.CommitUpdate();
            zf.Close();


            // Renames and saves the updated ODT file
            Guid g = Guid.NewGuid();
            string updatedFilePath = Path.Combine(Path.GetDirectoryName(odtFilePath), g + "_" + Path.GetFileName(odtFilePath));
            using (FileStream stream = new FileStream(updatedFilePath, FileMode.Create))
            {
                ms.Position = 0;
                ms.WriteTo(stream);
            }
            Console.WriteLine("The ODT file has been successfully updated and saved as: " + updatedFilePath);
            Console.ReadLine();
        }
    }
}