How do I get the Tab Groups functionality?

My Firefox app is updated to the latest version available (154.0.1 Build #2016180583). In multiple places over the past couple of months, I've seen Mozilla advertising Tab Groups for the Android Firefox app, but I still have not gotten this functionality. Right now on the Google Play Store page, there is a section that says "Major update" for "Tab groups. It's like therapy for your tabs." However, there is no new update available for me to select because it's already updated to the most recent version. How do I get the tab groups functionality? I've seen some mentions of this possibly being a phased roll out, but if that's the case, why is it be broadly advertised without any indication that it's not actually available to everyone yet?