Finally, AT&T has rolled out Android 6.0.1 Marsmallow to Samsung Galaxy Active. Technically, they are ready to rollout and file size is going to be around 1.4 GB. So before updating you should opt for Wifi Network.
Further, The update will arrive as software build UCU3CPE4 through a file which will include new version of Android and Touchwiz. In detail, Galaxy S6 Active is set to  get Google Now on Tap, Doze Mode (for better battery life), and better app permissions controls.
USers can check for the update by heading over to Settings>System>About Device>Software Update>Check for updates.
Anyone from here who have received this update on their device? Share some changes with us via comments below.