Can I adapt a baking recipe for a Dutch Oven to a Casserole Dish?
They are different terms for the same object, so yes.

In the images you have chosen the first is metal and the second ceramic; these would have different properties in terms of browning the food that comes into contact with the base and sides. But products branded as 'Dutch ovens' come in metal and ceramic, and products branded as 'casserole dishes' come in metal and ceramic too.



In addition, for the specific recipe you are using the author has added:


  You can use any 6 quart dutch oven, cast iron, enamel, Pyrex or
  ceramic bakeware (with lid) that can heat up to 500 degrees F.


So I would have no concerns about the equipment as long as it has the desired volume.