The Greenlots card that you receive from Kia has to be linked to one of your own credit cards. When you go to a Greenlots network, you flash the card, it's read, and the charger will work, and your credit card will be charged.
I now have eVgo card, Greenlots, and Blink cards. I've learned that you need to get one of each if you are going to have to stop to charge your car somewhere. It's like Chevron, Shell, and Exxon--different gas stations-- except that they take your credit cards and you don't need a specially linked card for each and every network. It would be great if some of these orgs merged, but such is life. If you don't have one of these cards, you can still charge as a guest, but you have to make a phone call, and the fee is higher.
The big thing is that we should ALL be urging Kia to follow Nissan's "charge up for free" program. This allows Leaf owners to charge their cars at certain networks (eVgo is one of them). Everywhere I go I meet Leaf owners who are at these charging stations "topping off" their power for free.
Kia customer service said they have no plans currently to follow suit. I urge everyone to make a call and register your desire.