It may take time to receive your purchase. If you did not receive the item right after the purchase, restart the game. If this did not help, follow the steps mentioned below.
1) Contact in-game support (Start the game - Settings - Help & Support);
2) Explain the situation, what did you purchase and when;
3) IMPORTANT! Add a receipt from Google Play
When you make a purchase, the receipt is created automatically and sent to your Gmail, that is linked to your Google Play account.