Can you help with PHP for Iyzico on the website?

[Capz]

Dear friends, my issue is with the integration of iyzico on my website. We have obtained the foreign theme API and key, and the payment goes through. However, it does not show that the order has been received, nor does it appear in the admin panel. However, everything works correctly when the purchase is made via bank transfer. Can anyone who understands iyzico integration please help? I would appreciate it.