How to put my Unity made game into Android Studio phone app ?

You'll need to have your phone plugged in to your computer, and have activated Developer Options on your phone (google how to do it for your specific android device). Once you have that on, turn USB Debugging on, and if theres an option turn your connection type to FTP (File Transfer Protocol). There is also an option for most android phones for instal protections. You'll need to turn that off, on mine it was called "allow downloads from unverified sources" or something of the sort. Make sure its off! After your phone is all set and plugged in, you should be able to use your phone the same as you would a usb. If you can access all of its files like that, you're great! Note: Not all charging cables are capable of FTP, some are just charging cables. The cable that came with your device should be capable, other ones vary. You may have to buy a new cable if that doesn't work.

After all of that, it's pretty easy. You should be able to build your game, and create an .APK file of it. If you press Build and Run in Unity, with a properly set up phone connected to your computer, Unity will download it to your phone for you and automatically start playing it. That's it! If you have any questions consult the Unity Guide for additional help, or leave a comment below with your specific problem, and at what point in this you are having troubles with.