According to a senior XDA Developer forum member who prefers to be known as the name of jrior001, this particular custom ROM comes in the form of the Android 6.0 Marshmallow CyanogenMod CM13 custom ROM for Zenfone 2.
Do bear in mind that the Android 6.0 Marshmallow custom files will not be the same as that on a certain device compared to another, so one should always be extra careful to make sure that the correct file is installed on your device in order to avoid any kind of untoward incident. Not only that, making a backup of all important data and information on your existing Zenfone 2 before performing an installation of the custom ROM makes full of sense. Or, you can always look out for the Zenfone 3 which is said to come with a fingerprint scanner.