Can I set a data usage alert even though I'm on a prepaid plan?

Hi, I'm on a $25/mo prepaid plan. I would like to set an alert so that I know when I've reached 90% of my data limit for the month. Is this feature available for prepaid users? The instructions I've found (https://forums.att.com/conversations/data-messaging-features-internet-tethering/how-to-set-up-a-data-usage-alert-to-40-of-current-data-package/5df016f7bad5f2f606a690dc) say to logon to the myAT&T app and then Usage>Manage Account>Data, Voice, or Text Alerts. However, when I logon to the app I get taken to the paygoonline.com, and there is no Usage or Manage Account section