I manage properties and have dealt with this many times. Use a solution of water and bleach, maybe 5 to 8 parts water to 1 part bleach. Wipe the entire insides of the fridge. Make sure you get the gooves in the seal, all around the door and all the shelves and bins. Then wipe down with baking soda water and place an open box or dish of baking soda in the fridge. This should take care of it.
In the freezer, if you remove every thing there maybe a removable panel on the bottom. There are two screws toward the front and two at the back. Remove those and you can lift this base out. It has little slats and stuff spills in there all the time. give that a good cleaning and your freezer will be much fresher.