The Analytics tab, accessible from the Klarna Payments app in your Shopify store, enables merchants to retrieve Klarna order data based on an exported Shopify Analytics custom report of Payments by method, availability dependent upon store's Shopify plan per:
https://help.shopify.com/en/manual/reports-and-analytics/shopify-reports/report-types. The input file for this report should be a CSV file exported from your Shopify store admin, from Analytics -> Reports of report type: 'Payments by method' including the column: 'Order ID' (exported as order_id in the CSV file). (Note: if a merchant does not have access to Shopify custom reports, the input CSV file can be manually created, but must still include order_id data, and Shopify order numbers, e.g. 1234563237123).
For each Shopify order, the Klarna order data will be attempted to be retrieved from Klarna, thus the number of orders in the report should be limited to a reasonable amount. If including Klarna settlement data, the number of orders should be even less as the settlement API is more resource intensive.
The order totals may differ between Shopify reports and Klarna data for reasons, such as: