Can I use an RT-AC66U as a wireless repeater?

I have an RT-AC66U, Windows 8. I recently changed apartments and the guy upstairs is willing to share his Internet connection. Since our work patterns are different, this seems a great way to save costs. The signal from upstairs is too weak to penetrate our entire apartment. It seem I ought to be able to use the RT-AC66U to pick up his signal and repeat it.

Here’s where I stand:
- RT-AC66U should function fine: Used until last week with a modem on same computer
- Can’t access configuration...

Can I use an RT-AC66U as a wireless repeater?