To change the language on the website you need to do it twice. First, just before logging in, on the same page where you enter the code, you have the option to switch the language in the upper right corner. Then, after logging in, you change it in the same way as in the mobile application by clicking on the person icon of the dashboard -> "Settings" -> "Language" (in Dutch: "Instellingen" -> "Taal"; in French: "Param├Ętres" -> "Langage").