TryNow requires a product.json file to function properly. Luckily, this file is included by default in all Shopify 2.0 themes. If you are on a Shopify 1.0 theme, you will need to complete one additional step to build this file and enable our app. To learn more about Online Store 2.0 vs. 1.0, please refer to Shopify's documentation on Theme Architecture versions and Online Store 2.0.
To determine if you have 1.0 or 2.0:
Log in to your Shopify store admin
In Online Store > Themes > click Actions > Edit code
In Templates folder of your theme, find product.json file, it exists which means your theme is a Shopify 2.0 OS theme
If no product.json file exists, you will need to begin the migration process and create a product.json file before continuing.