I have downloaded the latest Appium Desktop to inspect the different elements for automating an app. I was able to launch the calculator app on my Android phone but was unable to launch an app that I have installed from the APK.
These are the variables that I have used to launch the apps on my phone :
"platformName":
"deviceName":
"appPackage":
"appActivity":
DesiredCapabilities
for Appium. By reading the documentation and following the correct set of procedures, you will get it running in no time.