I think the problem is that you haven’t yet created a “basic” group on Discourse. You can do that by clicking the “New Group” button from the upper right of the Discourse groups page:
(my current screenshot program doesn’t let me annotate screenshots)
On the New Group page that opens, give the group the name “basic” and fill in any additional settings that you want to use.
Let us know if I’ve misunderstood the problem, or if you have any questions about how to create the group.