Play Magnus, If it was set to greatest strength. Carlsen definitely couldn't win a match against it. It is limited, however, so Carlsen would probably win.
The application is just an ordinary computer engine with set strength - "age". It doesn't seem to be even trying to mimic Carlsen's play, however. Just check out his own videos of himself playing the app - he says on a couple of accassions "I didn't know I played like that when I was young".
Here is a draw:
Always a draw.....hmm..