Apple pay certificates: 

https://developer.apple.com/help/account/create-certificates/certificates-overview

Apple pay identifiers:

https://developer.apple.com/help/account/configure-app-capabilities/configure-apple-pay

Apple Pay certificate creation:

Below is the link to create certificate for apple and there is a step by step process.

https://developer.apple.com/help/account/create-certificates/create-developer-id-certificates

After going this link:

• Create certificate
• Create identifier
• Create device
• Create provisional profile and the devices in provisional profile.

Apple Pay Plugin Guide:

I am using this code to create the apple pay plugin. Below link is for GitHub directory.

https://github.com/samkelleher/cordova-plugin-applepay

Below method we are using for apple pay:

Payment flow full example and response is given in the above link.

https://github.com/samkelleher/cordova-plugin-applepay

Enable apple pay in Apple store for your app:

https://developer.apple.com/library/archive/ApplePay_Guide/Configuration.html