CORS Error

With bKash popup, we are getting following error:

Access to XMLHttpRequest at ‘https://checkout.pay.bka.sh/v1.2.0-beta/checkout/payment/create’ from origin ‘https://shop.easytrax.com.bd’ has been blocked by CORS policy: Response to preflight request doesn’t pass access control check: No ‘Access-Control-Allow-Origin’ header is present on the requested resource.

How to fix?