It's a very broad category but 'services supporting the maintenance and existence of settlements' would definitely cover providing a way to make money off the homes/apartments in settlements like AirBnB and Booking does. It's providing a means of financial support to the people in the settlements.

I'm a bit confused about TripAdvisor but I bet there's just some portion of their business I'm not familiar with. It seems like reviews etc of businesses and lodgings inside settlements wouldn't be enough to reach that category.