Hi,
Try making your target folder a separate network share and then set up your user with just "read" access to that share. Make sure you don't have any "deny" access settings for the main volume. If the issues is your user / shares, this should help. If you have problems with the basic FTP settings, try going to YouTube and searching for Dlink NAS FTP Setup. There are a couple dlink TV videos which give pretty good instructions. Good luck.