I think the event will come out next week, since it will be the week of Halloween also think they might give some stuff out for not being able to have the summer fiesta this year
The event is open to everyone, but you need weapons and silver ammunition to kill the animals, you need the wolsbane revolver or the silver bullet crossbow or the silver bullet shotgun, otherwise you won't be able to kill the animals in the event.
Buy at least one of the weapons. This is the best event of the year and once you play it, you will start counting down the days for the next one immediately. It is really that good! Enjoy the event!