Run Steam Game As Admin. Running any software as admin ensures the app has full rights to modify files, access restricted folders , and edit the registry. If Steam doesn't have administrator access, it can act bizarre and produce unexpected errors.
Please carry out the The solution for running the game as admin. To get steam to run as administrator, you can right click on the shortcut, then go to "compatibility" and then at the The one that you right click should be the application or executable. For many users, Steam will automatically launch when you start.
When you run the game, it brings up one of those launchpads that auto-updates the client and all that good stuff.
Sometimes it also needs to change the system files so it can run in the most optimized way possible.
Right-click on any empty space, select properties, and click on the security tab. Are you sure you did that successfully? Running apps as an administrator in Windows gives them extra privileges.