Smart gestures are typically added by the manufacturer--they aren't a native feature of Android. Presumably, your ZTE phone doesn't have this feature.
You could try an app like
KnockOn (or one of the similar apps listed in the Google Play Store), but keep in mind that adding this kind of feature to a phone that wasn't designed to do it can increase battery drain (since the phone is essentially remaining awake in order to sense your finger tapping the screen).
Another Mod may have deleted your duplicate post in the ZTE forum, since we try to avoid having multiple duplicate posts in different forums. It makes more sense for this post to be in the ZTE forum than the Lollipop forum, though, so I'll move it there.