This module creates a new type of field, "protected files." They are still visible, but you can download them only with the necessary permissions. Handy, for example if a membership fee has to be paid to obtain certain information. You can set the rights with the default settings of Drupal.
Select the field in your content type.
For each file you can still decide whether or not to secure.
The view shows a lock.
In displaymode, you can choose which redirect to do. eg to the login form. The hover text can be set.
It only works if you have defined a private folder in the settings.php.