Cannot activate HBO with Unlimited Elite wireless service

One of the reasons I chose the AT&T Unlimited Elite plan was the free HBO. I have tried using the Access HBO link on your support page (https://www.att.com/support/article/wireless/KM1261921/), but that just leads to a page describing your unlimited plans.

I have already tried activating at atttvnow.com by testing the provided keyword to 2883, but I am told "Looks like your plan isn’t eligible for the HBO benefit. (Error code: 43408)", but clearly the plan is eligible.

This is getting very frustrating because I'm paying for this benefit but not getting it.