As Alturia said, you can use a Fixed schedule to do this, selecting Daily Interval, then 3 Days. But realize that you will not be using most of Rachio’s Smart features, but only the Weather Intelligence features you want, to prevent it from watering when it rains and other conditions. This means you will get the same water to your lawn or crop in August as you do in October, and will probably have to fiddle with irrigation times to keep things from getting soggy or too dry.
