You can, but there are some important limits. Plug the drive into the USB 3.0 port on the back of the node.
This is for local file sharing on your network only. It does not support FTP, a media server, or virtualUSB. It's also not intended for sharing peripherals like printers, scanners, or cameras.
In the Linksys app, go to External Storage to manage it. You can see which node the drive is connected to, check free space, and set a username and password for security. Crucial step: always tap Eject in the app before physically removing the drive to avoid data loss.