I have a problem during the process of downloading any application in the App Store. The problem occurs when I download the updates, not when I download a new application. Particularly, it appears a windows with this advice "Impossible to download the application. Impossible to find the URL on this server." And a red advice also, near the update button "An error occurred".
That's the wrong library for the Caches folder. The convention of using a tilde in a pathname:
means that it applies to your user account and means the Library folder in your user home folder. The user's Library folder is hidden in Lion; to get to it, hold down the Option key, and in Finder select the Go menu. The Library for your user will appear there. Select it, and then look in the Caches folder.