HDMI is for monitors, not for USB devices.
Some USB ports can be used as display ports, but the opposite won't
work. There are no USB to HDMI adapters for your use case.
Is your USB hub self-powered (ie. via a power adapter), or is it only
using USB ?
Same for the seagate, does it only have a USB port, no power adapter ?
Also, can't you remove the USB hub to plug the Seagate directly to the
computer ?
Do you have another computer and/or disk drive ?
PS: I didn't follow your previous posts as enough users were helping,
please gimme the name and/or URL so I can read it