Trying to dowload store purchase from iCloud on new macbook air

Question

All I keep getting is a message 'you must authorise this computer before you can download previous purchases". This mac is signed into my iTunes, iCloud and everything else on my apple account. I've even purchased a tune thinking that would authorise it but it hasn't. How do I authorise this mac please?

Answer 1

Hello kevindunn90,
After reviewing your post, I have located an article that can help with authorization issues. It contains a number of troubleshooting steps and helpful advice for the issue you are experiencing:
Authorize your computer using iTunes
You can authorize up to 5 computers, which means you can play your content on 5 different computers. To authorize your computer, you need to have access to it. You can't authorize a computer using your iPhone, iPad, or iPod touch.
How do I know how many computers are authorized?
If you authorized more than 2 computers, you can see how many are authorized.
Open your account in iTunes and sign in with your Apple ID. (Or open iTunes, click Store > Sign In, and enter your Apple ID and password.) In the Apple ID Summary section, you’ll see the number of computers that you’ve authorized with your Apple ID. You can’t see the names of those computers. 
Do I need to authorize my iPhone, iPad, or iPod touch?
You don’t need to authorize your iPhone, iPad, or iPod touch, but you do need to associate your iOS devices with your Apple ID. Your iOS devices don’t use your available authorizations.
How do I authorize a computer?
Open iTunes on the computer you want to authorize.
Choose Store > Authorize This Computer from the menu bar.
You might need to show the menu bar to see this option in Windows. In earlier versions of iTunes, you can access this option from the Advanced menu.
Enter your Apple ID and click Authorize.
If your Apple ID uses an expired MobileMe account, you can still use it to authorize your computer.
If iTunes asks you to authorize your computer again, it won't use a new authorization. iTunes uses the same authorization for the same computer. 
I tried to authorize my computer, but I’m out of authorizations. What happened?
If you didn’t deauthorize your computer before reinstalling Windows or upgrading your RAM, hard disk, or other system components, your computer might be using multiple authorizations. Try deauthorizing your computer a few times until it’s no longer authorized. Then authorize your computer again, and it will use only one authorization.
Get help
iTunes keeps asking me to authorize when I try to play my content.
I need to deauthorize a computer or deauthorize all computers.
Thank you for contributing to Apple Support Communities.
Cheers,
BobbyD