What is the purpose of ApplePay Payment Processing Certificate?

We are using a third party gateway company to process the payment. They have provided me a CSR and tried regenerating what should I do with this CERT?

They are saying they do not need the CERT from Apple. We just pass the ApplePay token to them for processing. They even says I don't have to install in my server for encrypting token. So I am not sure what's the purpose of it. Doe anyone know how to use this Cert or what's the purpose of it? Thanks.

What is the purpose of ApplePay Payment Processing Certificate?
 
 
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