Android 4.4.2 blocks installations outside the Play Store by default. To bypass this:
If WhatsApp becomes unusable on your KitKat device, switch to one of these alternatives. They are designed for low-end or legacy hardware. whatsapp para android 442 install
WhatsApp servers may ping an 'update available' message inside the app. Tapping will take you to the Play Store, which will say "App incompatible," and you will be stuck. Tap "Not now." Android 4
The only reliable method to install WhatsApp on Android 4.4.2 is —manually installing the app using an APK (Android Package Kit) file. However, not any APK will work. Users must find the last version of WhatsApp that officially supported KitKat. which will say "App incompatible
However, some users report a workaround via "My Apps & Games" library: