The Klarna Payments for PrestaShop module can be downloaded from the PrestaShop Marketplace for free.
Once installed and activated, the module's settings can be found by selecting Configure next to the Klarna Payments module in your store's Module Manager or under the IMPROVE section: Payment -> Payment Methods.
Prerequisites
Test mode allows you to test your integration to ensure it is working properly before taking real orders, and is the default setting. Orders placed while in test mode will not cause any real money to be exchanged. Selection "Production" enables live (production) mode and orders that are placed in live mode are real, valid orders. You can sign up for test credentials here.
API endpoint specifies the region your credentials are valid for (Europe, North America, or Oceania).
You can generate your Klarna API credentials in the Settings (or Integration Guides) app of the Klarna Merchant Portal. These will consist of a username and password.
Once generated, you can enter these credentials in the API Username and API Password fields.
For information on the other tabs in the module's settings, please see the User Guide available within the downloaded module zip file; also available below: