Rakuten extension with Grubhub

Does anyone here know if ordering on Grubhub online with the extension works? When I first found out about Rakuten I would order Grubhub online with the extension on but I would never get the cashback. Later on I heard that the app is more reliable so I started ordering with the Android app. It does indeed work, and I usually get the cashback email around an hour later. However it is very laggy ordering Grubhub on the app so I thought I can try online with the extension again... but I just want some confirmation or tips on how to get cashback with GH online.

Thanks