The ASUS Zenfone 4 series was announced back in September 2017, all the models shipped with Android 7.1.1 out of the box. Premium models like Zenfone 4 Pro and Zenfone 4 was running on ZenUI 4.0, however ZenFone 4 Max comes with an older version of ZenUI 3.0. Asus promised to update it to ZenUI 4.0 and no timeline is shared, now the update is rolled out to the ZenFone 4 Max.
ZenUI also brings some additional features such as support for VoLTE (Voice over LTE) and VoWiFi (Voice over WiFi). In addition, the update brings Asus ZenFone 4 Max users enhanced double-tap gesture settings.
To check for the update head to Settings – About – System update to force the download on your phone. If the update is not available please wait for couple of days, as the update will be rolled out in phases.