It is recommended to use your real phone to test android applications, instead of using the Android Simulator.
The Android Simulator is slow, using lots of resources.

To use your android phone you must first activate Developer options:

http://www.greenbot.com/article/2457986/how-to-enable-developer-options-on-your-android-phone-or-tablet.html

You must install a custom Android OEM driver from here:

https://developer.android.com/studio/run/oem-usb.html

Even if your phone is already installed on your system and you are able to download data from it, the Android Studio doesn’t work with a regular driver.