Whether or not your Ford Focus ST has Android Auto primarily depends on the vehicle’s model year and the type of multimedia system it has.
If you own a Ford Focus ST built between 2013 and 2015, you don’t have Android Auto, but if you own a Focus ST built after 2015, your vehicle is equipped with a SYNC 3 (or newer) multimedia system, which is compatible with Android Auto.
To enable Android Auto in your vehicle, press the “Settings” icon at the bottom of your Focus’ touchscreen, swipe until you see the “Android Auto Preferences” icon, press it, and then select “Enable Android Auto.”
Once Android Auto is enabled, you’ll need to plug your smartphone into a USB port, after which you’ll be asked if you want to connect—click “Continue” and follow the prompts as they are given to you.
If you want to purchase an aftermarket Android Auto system, be prepared to pay $150-200 for the most basic system and $700 or more for a high-end one. Hope this helps!