Azteca is a broadcast network carried by a local TV station. WPMF-CD (broadcast channel 38) from Miami should carry it, but maybe they don't have a carriage agreement with Comcast. According to a Wikipedia entry, Azteca was being carried by WGEN and moved to WPMF on November 1, 2017. WPMF was 'My Family TV' before that.
WPMF's web site: https://www.wpmf38.com/
A bit out of date as it still mentions 'My Family TV'. Maybe you can use the contact form to see if Comcast is carrying them. They may be on another channel.