How to associate tivo to a tivo.com account?

I have a tivo series 3 HD with lifetime service bought from buy.com. When I tried to use the android app "tivo", it asks me to login to tivo.com. I have an old account but no device is associated with it, so the app tells me there's no device to use and logs me out.



How do I associate my Tivo to this account, or a new account? The only thing I see is "activate a tivo" but my tivo has already been activated long time ago.