More than one user in Nextcloud App

Within a projekt in preschools we want to use the Nextcloud App with multiple users on one iPad. If I sign up different users for the app they all have access to the folders from the others because you can change between users without entering the password of the account. Is it possible to have encrypted user accounts or to encrypt a folder with a password that is not the one of my account? I would like to make sure that the other users of the App can’t see the content of the folder.

Many thanks,