Did you register?
The fine print says:
Access to a selection of our Census, Immigration, Military and Vital records is free until July 2, 2013, 11:59 p.m. (ET). To view these records you will need to register for free with Ancestry.ca with your name and email address. Once you have registered, we will then send you a user name and password to access the records. If you haven't already, you will be prompted to register once you start trying to search and view the records. After July 2, 2013, you will only be able to view these records using an Ancestry.ca paid membership.