Account Settings > API Endpoint and API Endpoint (Secondary) according to https://epayments-api.developer-ingenico.com/s2sapi/v1/en_US/php/endpoints.html
Account Settings > API Key = Configuration Center provides the value
Account Settings > API Secret = Configuration Center provides the value
Account Settings > MID (Merchant id) = Configuration Center provides the value
Account Settings > Hosted Checkout Subdomain = can be configured on Configuration Center. By default it is: 'https://payment.'
Save Config
In magento root dir run command php bin/magento cache:clean
Test module
Open Magento frontend
Add product to cart
Proceed to checkout page
On "Payment Method" page click radio button "Ingenico ePayments"
Available payment methods under the title 'Ingenico ePayments 'will be shown (PayPal, Visa, etc.)
Support
In case of questions or problems, have a look at the Support Portal (FAQ):
http://ingenico.support.netresearch.de/
If the problem cannot be resolved, you can contact the Ingenico support team: