Can't install a simple app, We could not complete your request I'm trying to install an app on a Mac.

When I try do it I get this message:



I don't know how to fix this as no specific error message is being displayed.

I'm used to Windows, and there I just download the file and install it.
Is there away to avoid going through the App Store to download the program as it clearly doesn't work?
I've gotten error 4 in the past when my sign-in to the app store has expired. Try clicking on Purchases. If that doesn't prompt a sign in, try downloading one of the apps listed in there.

You should be prompted to sign in, and then you'll be able to download your new app.