DTD stopped running buses to the parks, because people used the free parking, instead of paying at the parks. There was no parking for DTD anymore for the shops and restaurants.
They only have the resort buses.
You can take a resort bus that would be closest to the particular park that you are looking to go and then transfer. Or you can just take a cab.
Or you can walk over to OKW or SSR and take a bus from there.
Or you can take the water taxi over to POR or POFQ and take the bus from there.