Membership Plugin URL Groups access rules

I'm trying to use Group URL negative rules to prevent the visitors level of my site to have access to single posts of a custom type, since I see Custom Types are not supported I assumed I could use URL groups to prevent going inside any /ofertas/* page, but after dragging the URL Groups element to the rules area, I just don't see where to add the groups or the place referred in this line: "Select the URL Groups to be covered by this rule by checking the box next to the relevant URL Group name.", which is the only thing I see, as you can check in the attached screenshot. Please help asap