U-verse apps

What are the correct instructions for signing into the Uverse apps using a FireStick.   

Most importantly,  what are we signing on with?  I am an authorized user with ATT/Uverse.  Have an ATT.net email and password.  But this doesn't seem to translate in granting access.

Please post the instruction URL for what sign in information to use and the CORRECT instructions for a FireStick.  Also Cannot post because the Add Tag section keeps putting me in a loop that requires me to remove any tags I've placed in the Add Tag section.