To add "Windows Insider: NinjaCat" stickers to WhatsApp follow these steps:

• Download the Sticker Maker app from Google Play (Android) or from App store (iOS)
• Download the "Windows Insider: NinjaCat" sticker pack if the download doesn't start automatically.
• Click on downloaded file WINinjaCat.wastickers and open it in Sticker Maker app.
• Click "Add to library" and then "Add to WhatsApp". Ok.
• Stickers added to WhatsApp! Thank you for using our site.