How to use [isxdl.dll](http://woohaeng.com.ne.kr/docs/isxdl.htm) to download files in C#?

isxdl.cs

[DllImport("isxdl.dll")]
static extern Int32 isxdl_Download(IntPtr hWndParent, String pszURL, String pszFileName);

[DllImport("isxdl.dll")]
static extern Int32 isxdl_SetOption(String option, String value);

private void button_download_Click(object sender, EventArgs e)
{
    var fileUrl = "REPLACE_ME";
    
    // use dll to download
    String downloadFolder = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments), "COMPANY", "Downloaded Updates");
    if (!Directory.Exists(downloadFolder)) Directory.CreateDirectory(downloadFolder);

    String downloadedFile = Path.Combine(downloadFolder, Path.GetFileName(fileUrl));

    isxdl_SetOption("title", "Downloading Updates");
    isxdl_SetOption("label", "Downloading Updates...");
    Int32 result = isxdl_Download(IntPtr.Zero, fileUrl, downloadedFile);
    if (result == 1)
    {
      // file downloaded
      // ...
    }
}