If you have purchased on your mobile or the FITE website please check the email you have used to sign up for FITE. You can find it under https://www.fite.tv/account/profile/ or under the account menu in the FITE app.
Use this email to log into your TV app. If you do not know what your password is you can logout on your mobile/computer, click on "Forgot password?" and request a new password.