Several people have said they bought the season but got only one episode. You get the episodes after they are shown on TV. The below is information from Amazon about buying a season with episodes that have not aired yet.
When you buy a TV Season Pass, episodes that have already aired on TV are immediately available to watch from Your Video Library.
New episodes are automatically added to Your Video Library as soon as possible after their original network air date (usually the following day). We'll send you an email notification when new episodes are available.