As long as the integration is active, a Mollie QR code automatically appears on your invoices. Your customers can use it to pay your invoices by scanning the QR code with the camera or QR function of their smartphone. The scan takes them to a payment page where they can pay your invoice with the payment method of their choice.
To check whether the integration is active, click the 'Integrations' submenu in the 'Settings' menu. Scroll to the Mollie tile and click 'Installed'. The next page shows the status of the integration.