Sorry if this sounds obvious, but is she sure she's logged in with the correct Square Enix ID? Also does she perhaps have more than one service account registered to the same Square Enix ID and she might need to change it in to the other one which actually has the game activated on it (it can happen if say converting a trial to a full game, but instead of converting the trial the game is added as a new service account/new characters).

If you haven't already I'd recommend contacting Square Enix directly though. These forums are really only for customers to help other customers, but with things like billing/account issues you can only really get help from SE directly.