Since the last update, the referral code has to be entered after creating your WeWard account.
Please note that you must do this within 48 hours of creating the account. A counter will tell you how much time you have left to enter your referral code. It will not be possible for you to add it later.
On the other hand, if you created your account more than 48 hours ago without using a referral code and you really want to take advantage of it, you can delete your account and create a new one to enter the referral code.
To enter it: go to the app settings and click "Enter my referral code". Then enter the code that was sent to you and that's it!
The person who referred you will receive a notification saying that you have added his code. If he doesn't receive it, try to enter the code again or contact our customer service to be sure the code has been taken into account: firstname.lastname@example.org.