Hi, please try running the following code (change targetPath first to an existing directory):
string targetPath = @"c:\temp\downloads";
using (var client = new Sftp())
client.LogWriter = new FileLogWriter("log.txt", LogLevel.Debug);
client.Download("*.png", targetPath, TraversalMode.Recursive, TransferMethod.Copy, 0);
If it works, try to modify it to download files from your server. If that still doesn't work, send us the communication log (log.txt) created by the application. If it does work, delete downloaded files, change TransferMethod.Copy to TransferMethod.Move and try again. If it doesn't delete the files this time, send us the communication log for analysis. Thanks!