Thanks @tomw, the Shelly Uni driver is awesome.
I figured out why I couldn't configure the Shelly Uni on the configuration page. I put in the IP address as http:// 192.168.50.202/, which didn't work. So, I changed it to 192.168.50.202 and it started working and gave all the child devices.
Then I configured the "Shelly Uni for Reef Tank-adc0" to read the correct voltage, since the default voltage offset was -0.4 volts. I changed it to "-0.0" and it worked.
I was then able to create an alert app that sends a notification to my phone. Although, a tricky part was I had to use "Custom Attribute" as the capability of the Trigger event
It works perfectly now 
