For Magento 2 in particular your Marketplace purchases you must ensure that you have an account with Magento.
Please visit https://www.magentocommerce.com/products/customer/account/login? and Register.
When logged in click the Connect tab, then under Developers click Secure Keys. When the page loads you will see a simple form, enter ZERO-1 into the Name field and click Generate New
You will then be provided with a Public and Private key pair, please copy these and email them us by clicking this link