Hey Mark! Your plan should absolutely provide you with mobile data to use away from Wi-Fi.
I'd first please check that your mobile/cellular data is turned on in your settings. If it is, can you please turn your Wi-Fi off and see if you have a 3G, 4G or LTE signal on top of your screen? If that is not the case, please reach out to our live chat support between 10am-5:30pm EST for further assistance :)