Unfortunately not every app allow third party emoji/sticker apps, and Facebook is one of them 🙁 We can only hope those apps soon update to allow third party stickers. Currently the ones we know for sure works are iMessage, Telegram and Mail.
Emojis are fun, football is fun, so why not combine them. Have your favorite national team or favorite players right at your fingertips. Football Emojis can be downloaded on the App Store both for iPhone and iPad, so what are you waiting for, Shoot!