Saturday 21th, you can go to la Aldea by train or bus and then, a free bus shuttle will take you to MónNaturaDelta.
Also, there will be another bus shuttle which take you from Platja del Trabacudor to MónNaturaDelta every 15 minutes. So in case, you have parked far, you can easily arrive to festival. Or if you prefer to come by bike, Deltacleta service can rent you electrical bikes.
More information here.