For the Netherlands
No, Flex is not a payment option but a credit. So it is not possible to chose for Flex when you want to complete your order online. Moreover, a credit is accepted on the basis of a credit check. You choose to pay via Riverty in the check out at the webshop. If you qualify for the Flex credit, you can add an order to Flex via the app. Read how to add an invoice to Flex here.
Certain products can be paid with Flex. Click here for an overview. For which products can I use Flex as a payment option? – Riverty Support