Hah-hah. No. There's a reason why the price includes "approx." I clicked the ? and got these statements:

El precio medio es un indicativo para que el viajero pueda hacerse una idea del precio aproximado del alojamiento y pueda compararlo con otros.

Este precio se calcula haciendo una media con los precios por noche de todas sus opciones de alquiler, durante los siguientes 6 meses.

No se contemplan en el cálculo las ofertas especiales, ni descuentos por número de noches o personas.

Para saber precios más exactos sobre el alojamiento, introduce tus fechas y plazas en el buscador.

Google Translate gives:

The average price is indicative so that the traveler can get an idea of the approximate price of the accommodation and can compare it with others.

This price is calculated by making an average with the prices per night of all your rental options, during the following 6 months.

Special offers, discounts for number of nights or people are not included in the calculation.

To know more exact prices about the accommodation, enter your dates and places in the search engine.

The 15€ per person per night is if you have 12 people and calculate the cost per person. In the statement they say that the value is using six months of rates of all your options so you can better compare properties. That's pretty misleading if they're dividing the nightly rates by the maximum number of people who can stay.

The actual nightly rate appears to be 180€, which I found when I tried 2 people, 2 nights for a weekend in March. That works out to 15€ per person per night if you have 12 people staying.