Use the automatic onboarding flow in your Adyen Customer Area to add Klarna.
To add Klarna to your Adyen integration, follow these steps:
All the heavy lifting is done and you will receive a Klarna activation email within a minute.
Depending on your Adyen integration, you may need to perform some additional steps to make Klarna available in your checkout. Please note that line items are required for payments request towards Adyen to initiate a Klarna session. For more details, please refer to Adyen Docs.