@Ed344 You can't possibly gain enough money from such a request to be worth the hassle. It's not a straightforward process.
But you should definitely post a public response to the review stressing to future guests that your maximum occupancy is 5 and you did not permit any additional people to stay.
You should also update your House Rules to state that no unregistered visitors/guests may enter the property, and have a plan for how you'll react the next time you catch guests sneaking extra people in. This guest clearly had no reason to think they couldn't get away with whatever they wanted, so it's lucky that things didn't go worse.