Hi @latte. Yes, a Ring Bridge is required for any smart controls on any Ring Smart Lighting devices, as the Ring Bridge is how they connect to the Ring app. Without a Bridge, the Ring Transformer cannot be connected to the Ring app and you will not have access to Light Schedules or be able to turn the lights on or off in the app.
As for the product page, you’re not seeing an Add To Cart button as the Ring Transformer is currently out of stock. If you click on just the Transformer option on that product page, it gives you an option to enter your email address to be notified when it is back in stock. Apologies for any inconvenience or confusion.