How do I apply for the att low income internet discount?

Safelink does not provide internet in Alabama.  

You’re looking at Lifeline home phone and internet service with At&t.

https://www.att.com/home-phone/lifeline.html?source=ECmj0000000000mbD&wtExtndSource=lifeline

The only low income plan att has for internet ($10/month) is the AT&T Access program.  Check there to see if you qualify.