The installation is carried out from a webwinkelfacturen.nl page. After entering your details via this link, you will receive a guide and a link for setting up the connection between Billit and your webshop.
You can try the integration free of charge for the first 30 days. After that, the integration does not automatically become paid: you will first receive an e-mail asking you to choose a pricing plan based on the number of invoices you transfer. More info about webwinkelfacturen.nl's pricing can be found on their pricing page.