Click 
in the main toolbar, select the folder/file to copy in the list on the left and dragging it to the folder where the copy is to be saved in the right panel.
In the Copy/Link pop-up, select Link from the menu to create a link between the original and the copied file or select Copy to create a separate copy of the item.
For folders, check the Include all subfolders box to link/copy all subfolders and their content as well.
When linking items, check the Auto Update box to automatically update the destination file(s) if the linked source file(s) are updated.
When copying items, check the Notify box to be notified when the source file changes.
(Notifications are automatically sent for linked items when the source file changes.)
Because you are making a change to the contents, an electronic signature is required for copying and linking.
When linked, the icon for the linked file changes to 
and the menu options available when clicking 
include Get Latest, to update the linked item with any changes that have been made to the source, and Unlink, to remove the connection.
Note: When a file is copied or linked to a folder, the copy or linked version will inherit the permissions of the folder to which it has been copied or linked. It does not retain the permissions of its source folder.
To unlink a file
In the Copy/Link panel, click for the file to unlink.
Select Unlink in the pop-up menu.
In the Unlink pop-up, click OK to remove the file from the location.
Or
Check the Keep as a copy box and click OK to remove the link, but keep the copied file in the location.
Unlinking requires an electronic signature.