I love the suggestions by ⭐Princette♥PengthuluWrites and Elle . Remembering that you only have to spend 15 minutes per assignment, you probably don't need additional suggestions, but in case you're interested... consider picking one or two random members of the organization and profiling them. They don't have to be the "face" of the group in the story. The individual(s) would just be the face(s) of the group for you, mentally. Who is this arbitrary, anonymous person, and why do they belong to the group? What's in it for them? What goals do they have? How do they hide their association with the group from family and loved ones? Describe their two lives - the life they lead in public, and the secret life they lead in which they, somehow, affiliate and participate with this group who antagonizes your main character.

Groups are made up of people. People have individual personalities and motivations.

Cheers,
Michelle