Outdated text on the Zotero wiki
https://www.zotero.org/user/register/ mentions "You need a Zotero account to use the forum or if you are participating in the Zotero 2.0 sync preview.". This should probably be something like "You need a Zotero account to post to the forums or to use Zotero syncing."
As Dan has repeatedly stressed on the Zotero forums (e.g. http://forums.zotero.org/discussion/14519/how-to-backup-zoterosqlite-with-mozy/?Focus=71650#Comment_71650 ), syncing is a poor substitute for backing up a library. In addition, the "back up your all your attached files" links to http://www.zotero.org/support/file_sync. My recent changes to the wiki deprecate this page. Instead http://www.zotero.org/support/storage can be used.