Plugin for Restricted pages without using 'User roles'

Hi!

I’m looking for a plugin where you don’t need to code and you can give people restricted options for different pages, but not using the user roles WordPress provide.

I’m developing a website where different people need to be able to add posts on a existing page. But those people can only see this particular page and not the admin of the complete website. So there will be somewhere around 40 different people who can all only see the one page that they are assigned to.

All the pages together will form a website open to the public so it’s only for the admin area that I need this plugin.

Is there a plugin that will allow you to do this?

Thank you for helping.