How to integrate HitPay to axelor

I’m really a newbie to axelor. There is a request from the project that wants to integrate POS into axelor (HitPay). I’m not understanding by what mechanism axelor receives data from hitpay and vice versa. Can you give me a solution?
https://hit-pay.com/docs.html#paynow-apis-and-payment-request-apis

yes, we can do it easily, axelor provide all such material, https://docs.axelor.com/adk/5.4/dev-guide/web-services/rest.html

i am assuming, you have to integrate this api
https://hit-pay.com/docs.html#webhook