That will not work.
Section Access only works in combination with a server. The free cloud version does not offer you the server functionality.
You might notice that the Section Access table for Qlik Sense does not have a password column. In Sense the username+password is checked when you login to the Hub. The app after that only uses the username to define what data you can or can not see. Without a server, that username+password check does not happen and the app will as a result ignore who you are.