you want to use the HDMI out and the HDMI cable supplied with your Canon VIXIA HF R700. For me, once I connected the appropriate cables, the video capture appeared in my video capture software.
This is what I used to capture HDMI out from the R800: Magewell XI100DUSB-HDMI USB Capture HDMI 3.0 HD Video Capture Dongle
I'm no elgato expert, but it must be a fairly easy transition with the R700? got to be something just missed or overlooked.