Do you need a Raspberry Pi for this to work? Or would it work if I plugged it into my windows 10 mining rig which is
currently running 2 vega 64's ?
Well you 'can' use the mining rig, but it's far from ideal.
A cheap little RPi dedicated to doing the mining is a better idea than having a computer with various issues regarding the CPU usage that may delay your shares/blocks at random times.
It's not a case of "Yeah this computer has plenty of spare CPU",
it's a case of what are the peaks in CPU it uses doing other things (GPU mining, 'Windows 10', etc) and thus what effect that has randomly on the USB mining.