You've successfully compiled your first Android app - congratulations! Now, how do you get it onto your phone from your Mac? You could email it to your phone, or download in a browser, or from a chat app, or you can use Android File Transfer, as documented in this lesson.
Go to https://www.android.com/filetransfer/ and click Download Now.
Drag the Android Icon across to install in Applications.
Open Android File Transfer, and connect your Android device to your computer using a USB cable. On your device, go to Settings, then "Connected Devices" and then "USB". Turn on "Transfer Files".
Drag your app into a folder in the screen that appears. Downloads is a good folder to choose. If you don't see a screen, check that you have file transfer enabled in your USB settings on the phone, and that the phone is unlocked.
On your device, go to Files
Go to Downloads (or whatever folder you put your file into). Double click the app you are installing.
You may get this warning. If so, click "Settings".
Enable "Allow from this source".
You may get a request to allow certain permissions here that your app needs, but in this case, our app doesn't seem to need anything special so we just click "install".
Our app is now installed successfully on the phone. You should be able to see it on your home screen, either with a default Android icon, or the icon you set for the app.