Building a full android project from Unity takes extra time and may cause build issues (in my experience with Google Game Play Services). If you can avoid it, you’ll multiple the speed of your dev time.
Debug Android Device without Creating a Project with Unity
To do this, all you need to do is build directly to a device, open up your terminal, and paste the following:
adb logcat -s Unity ActivityManager PackageManager dalvikvm DEBUG
The -s option filters out everything except the filterspecs/tags you list afterwards. This command should be sufficient for most use cases, but you can always checkout the documentation.