Kindly advise on how to integrate HDFC payment gateway to our Admin panel.

The APIs of HDFC is already integrated with StoreHippo. You just need to create your account with HDFC and provide the credentials that you get from the HDFC dashboard in the StoreHippo admin panel.

Follow the steps mentioned in the below link to activate the HDFC payment gateway on your store:
https://help.storehippo.com/topic/setting-up-hdfc-as-the-payment-gateway