New MacBook Pro issues

I recently purchased a new MacBook Pro and can not download anything from the App Store. Nothing. It asks for my Apple ID and password, which I enter but my face never pops up and when I select the app to download the little wheel turns and eventually I get an error message that says apple.commerce.client.error 500

I've gone to iTunes and made sure all my information is correct.

Please advise - this is extremely frustrating.