Found my way through the labyrinth of settings to locate the free trial. I'll post this to General Discussion as well.

1. From the main page for the game, press the (...) button and select View Product.

2. On the product screen, press the (...) button again and select Free Trial.

3. Press the "Free" button, which brings up an Order & Pay screen. Confirm this.

4. Install the trial (instant install) and you will regain access to the main non-trial game.