Depends how long ago they quit, if there's still silver in their claim then it's a crime. No silver, no crimes. (you can tell when you try to interact with objects with criminal acts off, it says the land belongs to them. If it doesn't say that then you don't need to turn on criminal acts and you don't need to leave scents for borrowing stuff)
As for getting off the claim, you could try and bribe carver to reset the server for a bugfix to get a free port out early minus the contents of your inventory ofc

(this is intentional, right? ...not that I've been doing this... probably...)