Are you sure of the VRBO #? When I went searching for this rental, it took me to a place in Mexico.
The Octagon House is in Mal Pais, Costa Rica.... I likely would choose to send the kids to Mexico and spend my vacation in Costa Rica too!!! (just kidding!) ;~)
Please reconfirm the VRBO # and I may be able to help you, but if you are looking for a rental in Mal Pais with a nice swimming beach, this is not the place to be. Mal Pais has very few nice beaches....and only one on the very south most end of the road for swimming! Most are rocky shores and a few small nooks with a bit of sand. If you want nice beaches, you have to look at Santa Teresa and north. For families with young kids, I would suggest northern Santa Teresa, Hermosa and especially Manzanillo (which specifically has no big surf due to the natural reef just off shore protecting the area).