No PowerCMS does not have the ability to have multiple users and limit which pages can be edited by a certain user, it is limited to one administrative user.
What you could do is create a PowerCMS instance for each user, each with its own powerCMS Database, for example
connects to database: cms_user1
connects to database: cms_user2
connects to database: cms_user3
connects to database: cms_user4
This separates out the individual users pages into separate databases, you just have to be careful when putting the site together to display the content.