Steam asks for a new code during installation

It is common during the installation of some games, at some point the installer requires to insert  a new code.

This code that is requested is not the activation of the product. If you enter the activation key, it will appear that the key is invalid.

The code that this part of the installation refers to, is available in the right-hand corner of the screen on the game page inside your Steam. Notice that in the right corner of Links, there is the option Product Code. Just click that a window will open. Enter this code that will appear to continue the process.