AT&T is now pushing Android Marshmallow update for Zte Zmax 2 smartphone users in USA. It carries new build number Z958V1.0.0B24 and November month security patch for your handset. It will also update your android os version to 6.0.1. To receive the marshmallow update earlier build version must end with B12, B19 and B21.

The download file size is huge 1.1GB and will be available through FOTA. If the software update arrives your device Initialize the download with wifi network. If you continue to download update with mobile data your device may disconnect. You can check for manual software update by Settings > AT&T Software Update > Check for update. After completed the installation you can verify it from Settings > About phone.