static void Main(string[] args)
{
    try
    {
        SessionOptions sessionOptions = new SessionOptions
        {
            Protocol = Protocol.Sftp,
            HostName = "SERVER_URL",
            UserName = "USERNAME",
            SshPrivateKeyPath = @"C:\PuttyPrivateKey.ppk",
            SshHostKeyPolicy = SshHostKeyPolicy.GiveUpSecurityAndAcceptAny,
            Timeout = new TimeSpan(0, 0, 15)
        };
 
        using (Session session = new Session())
        {
            session.FileTransferProgress += SessionFileTransferProgress;
            session.SessionLogPath = @"C:\connection_loss_log_1.log";
            
            // Connect
            session.Open(sessionOptions);
 
            if (!session.FileExists(fileToDownload))
            {
                Console.WriteLine("File does not exist!");
                session.Close();
            }
            else
            {
                RemoteFileInfo remoteFileInfo = session.GetFileInfo(fileToDownload);
                remoteFileSize = remoteFileInfo.Length;
 
                // Download files
                TransferOptions transferOptions = new TransferOptions();
                transferOptions.TransferMode = TransferMode.Binary;
 
                string fullDestPath = Path.Combine(destinationPath, fileToDownload);
                TransferOperationResult transferResult = session.GetFiles(fileToDownload, fullDestPath, false, transferOptions);
 
                // Throw on any error
                transferResult.Check();
 
                session.Close();
            }
 
        }
    }
    catch (SessionLocalException sle)
    {
        Console.WriteLine("SessionLocalException " + sle.Message);
    }
    catch (SessionRemoteException sre)
    {
        Console.WriteLine("SessionRemoteException " + sre.Message);
    }
    catch (Exception ex)
    {
        Console.WriteLine("Error in ProcessEdi() while downloading EDI files via FTP: Message:" + ex.Message + "Stacktrace: " + ex.StackTrace);
    }
Console.WriteLine("End.");
            Console.ReadLine();
}
 
static void SessionFileTransferProgress(object sender, FileTransferProgressEventArgs e)
{
    long currentSize = (long)(remoteFileSize * e.FileProgress);
    Console.WriteLine("Progress: " + currentSize +" of " + remoteFileSize);
 
    Console.WriteLine("OVerallProgress: " + e.OverallProgress);
 
 
 
    Console.WriteLine("==========================");
}