I've gone through the following steps in Android Studio to build an unsigned APK:
Build > Build APK(s)
Once the APK is built, I press the Locate
hyperlink in the popup in the bottom right hand of my screen to locate the APK in my Finder.
I put this APK on dropbox and open up the public link to it on the phone I want to test with. I download and install the APK on phone, and everything works fine. The app launches fine.
The only problem is that it doesn't seem to have a launcher icon associated with it.
Here's what's in my manifest file:
<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.RECORD_AUDIO"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity
android:name=".SelectCoin"
android:label="@string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN"/>
<category android:name="android.intent.category.LAUNCHER"/>
</intent-filter>
</activity>
</application>