Older Papillons do adopt fairly well into a new home and into a new lifestyle.
He often is well behaved, and learns quickly what the new owner ask from him.
But, pending where he came from, and gravity of his attachment to the previous home, he may live with you for many weeks without much play, and he appears to you as a very quiet sweet dog.
Ever so slowly he will let you get to know him, and he will start to run around more, or he will pick up a ball.
From my own experience and other Papillon owner's experience as I know them, it can take a good 6 months to fully have your new friend "lived in".
So, be patient. Give him time and love, he will come around.