Poor thing, being crated with no place else to do his business has really confused his natural instinct. It may take him longer to re-learn a new behavior.

It might help if you always took him to the same place outside, that you have designated his potty area. Then it will begin to smell like the right place to him. And teach him a potty signal that you always use.

You might even try this when he wets in the house: clean it up with an old towel and take the towel out to the potty area outside and leave it there to strenghen the smell association.

And be sure to eliminate any smell inside with an enzyme cleaner designed to counteract urine. Get this at a pet store.

He is still young, so be patient. I think many dogs still have accidents inside at that age.
It is so great that you are willing to work with this pup. I'm sure he will bring you lots of joy.