Try the Btool Lite freeware first. It allows you to check if the app is compatible with your BMW and your OBD adapter. If you have questions or need help, send me an email. You can find my address at the bottom of the page. No connection: if the adapter and protocol settings are correct and the app still fails to connect to the car, try stopping all diagnostic applications in Application manager (including btool) and try to reconnect.
Supported Android Devices : [4.0.3–4.0.4] Ice Cream Sandwich - [4.1–4.3.1] Jelly Bean - [4.4–4.4.4] KitKat - [5.0–5.0.2] Lollipop - [6.0 - 6.0.1] Marshmallow - [7.0 – 7.1.1] Nougat - [8.0-8.1] Oreo -  Pie