How to log into the ATT DisneyPlus channel

I recently added the Disney Plus channel.  I can see the channels in my lineup.  However, I would prefer to use the Smart TV app for DisneyPlus.  I cannot find the directions for how to use the TV app via a link back to my ATT account.  Is there detail somewhere which will help guide me.  The ATT rep told me just to use my ATT log in info.  But Disney wants an email address - not the normal user ID I use to log into my ATT account.  Do I use the ATT email address and my the password associated with the Disney channel?  Thanks.