Hi @limonne and welcome to our adorable Community 😊 I did the same some time ago. Don't worry, I will give you the link with the instructions on how to make a King account and sync it with your Facebook.
Please note that this has to be done on your PC or you can also do it on your phone if your browser supports the desktop mode.
I hope this will help you. Let me know if you need more assistance. If you find this useful, please click on "accept this answer". Have a wonderful day 🤗