Have you looked in your game whether it has been added or not? I usually get the mail, follow the link, (had to update app first this time), choose which world I want to go to (you will only get it in the first world you enter per profile) and then it either takes me there or it crashes out. That is how it usually is for me. If I then go to the game to check if the 100 crystals are there, it is.
@Harry12Neo On PC, click the gray wheel in the bottom right of your screen. Click the question mark on the pop-up. When the support page opens, click the button that reads "Contact Us". Fill out the form you see on that page. When you are done, click the green button to the bottom right that reads Create. There you go.