emulator-5554 unauthorized for adb devices

Android emulators have by default "Usb Debugging" in settings. You just need to wipe the data of the emulator. Do the following steps. It will work :---

1. Close the emulator and run the command adb kill-server in the command prompt. If adb is not set in you path then you might run this command from directory where adb is present.

2. Click on Wipe Data option from avd Actions menu.

3. Now run the emulator. It should work.

In my case, Create a Virtual Device with Google APIs Image, not Google Play Image worked for me.

The problem occurs the only emulator that runs on Android Pie others don't.

In Android Studio

1. Open an Android Virtual Device Manager.
2. Create a new Virtual Device.
3. Select any Hardware you want.
4. Select any System Image which the Target is "(Google APIs)" not "(Google Play)" (If you don't found. Try to look at "x86 Images" tab or "Other Images" tab)
5. Done!