Creating an account on the site is not the same as having an active membership on the site. A paid membership offers additional features and privileges on the site that a basic account is not eligible for. One of these features is to use the servers Print to PDF options, as well as a Printer Friendly version of the page. If you are interested in purchasing a either a Premium or Professional membership, you may view the benefits and pricing options from the Membership Options page.
If you are unsure of which status you currently hold on your account, when logged into the website, a block on the right sidebar is made available to you, which displays your current membership status. If it currently displays Basic, you do not have the required membership status to make use of the site print features.