What hanger is compatible with Shimano Claris RD R200? Trying to find a rear derailleur hanger that works with the Shimano Claris R2000 8 speed, on my REI Co-op bike. Have done  lots of searching on Shimano's site and Amazon and Google. What am I missing? I think Shimano doesn't have branded/proprietary  hangers; if that's the case, how can I find another brand of hanger that I know will fit? 

If helpful, the bike specs here: https://www.rei.com/product/106309/co-op-cycles-ard-11w-womens-bike.
Derailleur hangers are specific to the frame, not the derailleur. Do you not have a hanger at all or is it just broken? If it's broken, then it's usually not too hard to find a matching aftermarket one from Wheels Manufacturing or derailleurhanger.com. Have you contacted the manufacturer to see if they sell it separately?