Licking can be from allergies, pain, boredom or a combination. How old is the dog? You can always wipe off the paws with a wet rag after coming from outdoors. To try and remove allergens. If he starts licking or scratching elsewhere I would say it’s allergies. If he is fixed on one spot it may be mental because licking causes him to release endorphins that make him feel good and it soon becomes just a bad habit. He may need a drug like amitriptyline to break the cycle

But anything you can do to add mental and physical enrichment would help

Mental enrichment for a dog?

Ya better take it to a dog shrink Just lol.

If they’ve gotta keep a dog in a crate then they got no business owning a dog.
Just my opinion.

You’d be surprised at the ignorance. Too much “entitlement” to own a pet without enough investment towards a living being