Newly adopted barn cats

We acquired 2 tabby cats from an elderly homeowner who couldn’t take her cats to her new home. She was in the country as well so the cats are used to indoor/outdoor. Since we adopted them in the fall, we kept them inside our barn to get used to their surroundings. They have always shown interest in trying to get outside. We recently installed a cat door so they would have the freedom for that. My question is will they know now that this is home and know to come back to the barn? What things should I do for them, leave food inside or outside? I do have a collar on them with our phone number.