Can´t add Friends in Soda- and Candycrush

Hi @Kingschnuddel
We warmly welcome you to the Friendly King Community's Candy Crush Saga forum.😊

First of all, when you connect the game through Facebook, you will only find Facebook friends on the leader board. In this case, to add friends, you need to add friends on Facebook.
By connecting the game through a Kingdom account, you will get random friends. To add a new friend to the Kingdom, you will need to know the friend's email address and request the friend by email at the King.com page. Of course you will need a computer to do this.
You must choose one of these terms.
I hope I was able to provide some clarity for you, and if there is any other question or concern that I could assist you with, please do not hesitate to reach back out to me!
Have a good day.

If you've already synced the game with the Kingdom, you'll need to sync the game with Facebook first.This process can be single-timed and requires a computer. 
Of course you will use the same email for Facebook, which you use in the Kingdom.
Read here more https://community.king.com/en/blog/discussion/248899/create-a-king-com-account-and-sync-it-with-your-facebook-game-instructions-for-pc#latest

Thank you for your kind feedback about my answer – I am glad you are enjoying the community🤗