If I understand correctly, you want a device inside your LAN to connect to a FTP server in the Internet and upload file? Normally, if there are no specific restricments in the firewall (I guess it’s mikrotik in your case), you don’t need to do anything. If it doesn’t work anyway, it may mean that (1) either the FTP server doesn’t accept your connection for some reason, or (2) you have some rules implemented to your NAT/Firewall that don’t allow outbond traffic the way you are trying to do. We can help in the 2nd case if you post your settings here.