Go to "Monetization" --> "Payment Gateway" in your CMS.
Click on IP Payments (See Below Screenshot)
Type the API User Name, API Password, Account number & DL (Direct Link Values) (Which you have received after you signed up with IP Payments in the corresponding fields.
Finally, click on "Integrate Payment Gateway".
Note:
It supports payment methods including, Subscription, and onetime payment method i.e. PPV.