Windows 10 nightmare won't connect to Jefa Tech Repeater

I don't see what difference it makes that you're using a repeater. WiFi is WiFi. Take your computer to an area with known working wireless, either a mifi, phone hotspot or someplace like Starbucks / McD's.

Are you able to connect to that wifi?

If yes, then something's wrong with your repeater, not your computer.

If no, you need updated drivers for your computer's wifi module. You'll need to use a hard-wire connection (your repeater looks like it has some) to download the driver for your wifi module.