Premium account

If you have a paid subscription of Adobe Acrobat Pro DC, then you should be good to go to unlock the prenium editing features in the Acrobat Reader Mobile app... that is what the Premium Account is.

When you sign in with the mobile app you should use the same AdobeID that you provided when you registered your paid subscription of Acrobat Pro DC.

NOTE: The AdobeID should be the primary email address that you used to register your Adobe Acrobat Pro DC  with that paid subscription.

If this not what you paid for, and you don't have Adobe Acrobat Pro DC installed, then you won't be able to use the full desktop computer version of Acrobat Pro DC in your macOS.