What steps should users follow to install FM WhatsApp after downloading the APK file?

After downloading the FM WhatsApp APK file, users should navigate to their device's Settings > Security or Privacy and enable installation from unknown sources. Next, they can open the downloaded APK file from their device's file manager or browser downloads. Follow the on-screen prompts to install FM WhatsApp. Once installed, open the app and follow the setup instructions to verify your phone number and restore chats if needed.