Easiest cheap answer is likely a single drive attached to a router. If your ISP supplied router doesn't have a USB port, you can install an off-the shelf router as a client on your network and be off to the races. This allows access to the drive from any LAN attached PC and doesn't keep your...
I have had reasonable success with 8TB USB3 Seagate desktop expansion drives (8tb version of the 4tb you posted). As they are "desktop" expansion drives, they do require external power. A usb3 hub is pretty cheap and, as the drive will be used for archive purposes, speed isn't as critical. I...