Hi leonmanjyoume,
Thanks for visiting Apple Support Communities.
If you pre-ordered the album, you should have already been charged the pre-order price, as mentioned in the article you found:
When the pre-order item becomes available, your account will be billed for the pre-order, and the item will appear in the Purchased section of your account.
If the album did not download automatically, try resuming the download on iTunes for Windows or Mac:
iTunes: How to resume interrupted iTunes Store downloads
http://support.apple.com/kb/HT1725
You can also use the steps found in this article to download your purchases on a computer or iOS device:
Download past purchases
http://support.apple.com/kb/HT2519
If you are not able to download the album you pre-ordered, I recommend reporting the issue with your purchase:
How to report an issue with your iTunes Store, App Store, Mac App Store, or iBookstore purchase
http://support.apple.com/kb/HT1933
Best Regards,
Jeremy