The payment processing can take some time since every transaction goes through several stages. First, it is being processed by your payment provider, then by the App Store, and only afterward by our server.
If you haven’t received your purchase within 24 hours, please contact our Support Team at https://plrm.me/arena_support and attach a screenshot of the purchase confirmation letter received from the App Store and a screenshot of your Purchase History for iTunes Store.
Here is the instruction > https://support.apple.com/en-us/HT204088