How to download Mavericks

I clicked 'Software Update' and OS X Mavericks was shown
When I clicked 'Free Upgrade', the box of 'Sign in to download from the App Store' popped up
I typed my Apple ID and password to sign in, the box of This Apple ID has not yet been used with the App Store... When I clicked 'Review', the box of Apple ID Creation is not currently available on the MAc App Store popped up as well. I can only click OK but it's not gonna hel

The Apple ID and password are correct as I can log in to apple website and did the Apple Care by this email.

Anyone can advise how I should do?