In order for GoCardless to appear as a payment method when your customers are checking out or updating their payment details, you will have to:
1. Configure GoCardless to be displayed as a payment method for all your customers under Settings >> Payment Gateways (under Billing section) >> GoCardless.
2. Set their preferred currency to GBP, EUR or SEK - one of the three supported currencies in GoCardless. You can set a customer's preferred currency by navigating to their Customer Details page and clicking the Change customer details option or via the API using the preferred_currency_code parameter.
3. The embed parameter should be passed as false if generating the hosted pages via API. By default, the API call will have the embed parameter as true as these are generally used to embed hosted pages in an iframe in your website. However, as GoCardless requires a redirection to their page, this option will not be displayed on the hosted page if the embed parameter is set as true.
4. GoCardless will not appear as a payment method if you're using the Rhapsody theme. You can use Inspire, Minimal or Elegant themes that are supported for GoCardless. To change the theme, go to Settings >> Customer-facing essentials >> Checkout & Self-Serve Portal >> Themes (on the left panel). This point is applicable only to the V2 checkout pages as V3 doesn't support customizing the themes.