You will need a WiFi connection for smart charging features to be used. However, you may also use a mobile hotspot (such as the one on your phone, or an independent module) to manage a JuiceBox. Your JuiceBox will work as a standard charging unit in absence of WiFi, and any schedules or limits you set when connected to the JuiceBox will remain even if the JuiceBox is not connected to WiFi.
WiFi allows you to set charging schedules so that your EV avoids consuming electricity at peak times and to take advantage of Time of Use (TOU) rate schedules set by utilities.