Internet and Call/Text are two completely separate features. Think of it as your Cable TV and Internet you have at home. You can have one without the other, but unless you have both "features" on your account, you won't have both (e.g. I have just Internet from Comcast, I can't plug my cable into my TV and see cable television -- or, my grandmother had just cable television from her provider, she couldn't get a cablemodem and magically get internet)
If you're on a legacy plan that's old enough to just give you a few minutes you need, you probably don't have Internet available on the plan. There's a possibility you might be able to add Internet to the plan for some unknown amount of money, but chances are they'd make you get on a current plan that would cost probably significantly more. You'd have to evaluate what options are available and how much you're willing to spend for the awesome Google Maps ability.
That said, there's also a way to use Google Maps offline -- while you're connected to your home WiFi, you can get the driving directions set up and saved, then head out. It won't help you with traffic or other things. Here's a link I found on that: Download areas and navigate offline - Android - Google Maps Help
T_hanks you ___smplyunprdctble for the explanation - will investigate
availability of internet via my free Comcast wifi and see if that may
Your Comcast WiFi will only get you to approximately the edge of your driveway (depending on the strength of your router).
However, you can connect your phone to your Comcast WiFi and cache / download maps, as identified in my link above.