RAVPower is too weak to charge the battery of a Surface Book 2. The output is 9~12 V 1.5 A max. The power supply of the Surface Book 2 has an output of 15V 6A. That is much more. A suitable cable might exist (google for "surface book to usb charge"). In principle, you could charge the Surface Book via the USB-C port. Microsoft warns against this, though:
Yes, you can normally charge your Surface via the USB-C port. However, we strongly recommend using the charger that came with your Surface, as charging speeds with a USB-C cable can be very slow (depending on which power adapter and cable you use).
Either way, RAVPower has far too little "juice"