Glad to see that you tested the humidity, it will help if you open and close the door several time a day, it also depends how much you have drying in there, because all the moisture from the drying meat has to go somewhere.
With the use of a modern frost free fridge, when it cycles the fan runs removing some of the humidity.
If there is not a defrost cycle, I think it will be hard to remove the humidity unless you can vent the area. Like leaving it cracked open a little to help remove some. I’m sure someone with more experience will help you. There are a lot of good people on here that will give you advise worth taking.