Nighthawk XR500 create network folder greyed out

Trying to add a Seagate 6T Expansion desktop drive to router to create a network drive but even though all USB settings are on and all access methods are turned on the "create network folder" button and the "Safely Remove USB Device" button are both greyed out and hovering over them turns mouse pointer to a red circle with a line through it.  Any help will be greatly appreciated.