The option, “Folder”, is a way to update or archive a document on a physical hard drive rather than sending it by email.
The “Default” option you may see there will likely point to the C:\ProgramData\TARGIT\ANTServer\Exported Reports location on the computer where your TARGIT server is installed.
You can add more Folder Export options from your TARGIT Management client. Just keep in mind that the folders you add from there will be folders that are accessible by the TARGIT Server. Often, to make sense, these folders should also be accessible by the end-users.