When creating an order request in PayPal REST API they say there is a possibility to set 'landing_page' field in 'application_context' object to 'BILLING' to get a link for credit or debit card payment form. Unfortunately when I use 'approve' link from 'links' array from order response it always opens login form. What should I do to get a link to credit/debit card form when using 'BILLING' setting of landing page ?
Current PayPal checkout integrations don't use redirects, and that parameter is no longer used from what I've seen
Instead of redirecting, use the JS SDK for the approval flow. Here is a demo that fetches to a backend for creating and capturing the order with the API.
With this integration, the "Debit or Credit Card" button is present and will open inline on your own site.