1.If your folder is in your local network (LAN), the folder is shared in the LAN in the way that you have access from your computer to it, you could access it by using relative URL to the remote computer folder like: "\\RemoteFolder\\SomeFile.txt".
See details here about how to copy the entire folder:
MSDN Link[
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2.If the folder is over the internet, or is in your LAN and the folder is not shared for your user, you cannot access it at all and you should use a local service installed on remote computer that have access to that folder in order to copy its content.