Do you have a Verion FiOS TV? Because the only Verzon service this works on is those with FiOS TV. If so this question is better suited for the FiOS fourm.
WatchESPN app only works if your TV provider has deal with ESPN. Then you login in with your TV provider account login. Currently one must have a TV subscription from either Verionz FiOS, Comcast, Time Warner Cable, Cox, BrightHouse, Optimum, BendBroaband or Midcontinent Communications to use the app. In the spring it will be available to Charter TV subscribers.