To download them, go to this page: https://stickers.cloud/en/pack/good-omens-reaction-stickers and click on “ADD TO WHATSAPP” or “ADD TO TELEGRAM” or “ADD TO SIGNAL”, depending on which OS you are running (iOS or Android) and which app you want to use them on. First you add them to your stickers pack on StickersCloud/WSTick, then you go to the pack in the app and click “add to WhatsApp/Telegram”.
Those stickers are uploaded through an app called “WSTicK” on iOS and “Stickers Cloud & Sticker Maker” on Android. You will need the app to install them on your WhatsApp but the whole process is free. Only annoyance is the ads when you open the app that one time to install the stickers.