The most common reason is that the referral code was used too late.

To count as an eligible invite, BOTH conditions must be met:

• New player requirement: your friend must enter the referral code when they created their account no earlier than 24 hours ago.

• Progress requirement: your friend must unlock Arena 5.

   

Important note:

Reinstalling the game doesn’t reset the 24 hours window. If the account was created more than 24 hours ago, it won’t qualify as “new player”, and the rewards will not be granted.