Hot Download Whatsapp For Android 601 !exclusive! Link

To download WhatsApp on a device running Android 6.0.1 (Marshmallow) , the most reliable method is to use the Official Google Play Store

You likely downloaded an APK built specifically for a minimum requirement of Android 7.0 (Nougat) or higher.

This is the safest and most straightforward method. The Play Store automatically provides the correct version for your device and installs future updates.