Think of it like you had a vacation home at a nearby lake. Assume you paid cash. When you go to stay there for the weekend, you don't pay anything. But you are on the hook for maintenance, cutting the grass, a new roof from time to time, property taxes, etc.
DVC is the same way. When you stay on points, there is no extra fee. But you do pay annual maintenance fees, which cover maintenance and taxes.
You will also probably go more often. So budget for park tickets and nice meals.
I do set up a credit card when I check in. This is because it is very convenient in the parks, resorts, and Disney Springs to pay via Magic Band. If you have a credit card that pays rewards for travel, this has the added benefit of converting any meals, souvenirs, tickets, etc. that you charge to the Magic Band into Travel expenses, which get you 5.25% cash back, on one of my cards.