Yes! Stations can always preview the audio without subscribing, but they would need to subscribe to access the files. If you would like to publish a special episode and make it available to all stations as a way to build interest in your show, we recommend publishing the episode in a "Specials" series. Any episodes published outside of your automated series (to the "marketplace") will be accessible to all PRX members.
The process for publishing to the marketplace is a little different than publishing to your regular series. You can find a tutorial here.