Californication instrumentals DO exist, but are currently being held closely by traders. Very closely lol. I'm not sure if they'll ever all be liberated...but they do exist.
It means that the instrumental version of the track 'Easily' was bought by someone for hundreds (or even thousands) of dollars, and that person is keeping the track to themselves until they can trade it for another song they want or sell it for even more money. It's not something I participate in, but it is what happens. If we're lucky, the track will get sold or traded so someone who is willing to freely share it.