Install OpenVPN Connect app from Google Play.
Open OpenVPN Connect app.
Click to menu.
In the "My Account" download OpenVPN files for Android and extract the Zip archive to any folder. Then transfer .ovpn files on the SD card of your Android device.
Click Import Profile from SD card.
Username and Password VPN can be found in the "My account".
Connect to OpenVPN server on Android 6 Marshmallow. Click Ok.
Connection successfully established.