To download and use stickers:
1. Open any chat or group.
2. Next to the text input field, tap Emoji > the sticker icon.
3. To add sticker packs, tap the plus icon.
4. In the Stickers popup that appears, tap the download icon next to the sticker pack you want to download. A green check mark will appear once the download is complete.
5. Tap the back arrow icon.
6. Find and tap the sticker you want to send.