It should just turn on. You don't have the ON/OFF pin connected to the input voltage do you? That would turn it off.
Why use an isolated regulator instead of just adding in something like a 60W AC-DC 12v power supply for less than $15?
https://www.amazon.com/GALYGG-110V-220V-Universal-Regulated-Transformer/dp/B06XRBYN4Z/
Do you have a wiring diagram?