The reason you couldn’t easily create the shop1 user is because we didn’t give you permission to do so
We’ve updated the demo configuration, so you should now be able to add the shop1 user and test the discount application.
Hello @dgiraudaudine,
Thank you for bringing this to our attention, we were able to add the groups plugin to the demo and the discounts are working.
You will also find in this tutorial the different types of discounts you can configure with the groups plugin
here