i cant buy items in the game

Welcome
Dear customer, make sure to add a payment method to your account on android open the play store then click on Account

click add payment method 

choose add credit or debit card then enter the card info

for iPhone go to Settings then click on your apple id

click on payement & Shipping 

click on none

click on Credit or Debit Card 

enter your name and card number

enter the card info then click save

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Best Regard
Yousef Saleem