Important: On Android 8.0 (API level 26) or above, the app may not works due to "Background execution limits" introduced in Oreo to improve battery life.
To overcome this, follow below steps:
(1) goto the "App info" screen
(2) then select "Battery > Battery optimization"
(3) set filter "All apps"
(4) locate and select Chinese Calendar Widget
(5) select "Don't optimize", then "DONE"
(6) restart app to confirm is working

A resizable Chinese calendar widget that shows the Lunar Year, Zodiac, Lunar Month & Date.

Note:
This doesn't open, it is a widget not an app. Add on home screen with

Menu -> Add -> Widgets -> Chinese Calendar Widget or

Apps -> Widgets -> Chinese Calendar Widget

The code is open source and available on github: https://github.com/HairyRobot/ChineseCalendarWidget