Why does battery optimization require to be disabled?

Battery optimization settings helps conserve battery power which is why it is turned on by default in Android devices.  
If Battery optimization is enabled for FeetPort, the app is restricted from detecting device location and many of the app’s functionality is lost as it is no longer allowed to function properly.

Steps to turn off the battery optimization:

  1.  Go to device settings, under 'Battery' option.
  2. Turn off the 'Battery Saver' mode.

Related Link:

 How to disable battery optimization