The ismartgate device connects directly (via two wires) to your opener, see compatibility checker for more information, and the sensor (required for any 3rd party app to function) needs to be placed on your garage / gate door, see more information about the placement of the sensors here. Once that is done, you can configure it all from the ismartgate Access app to use it locally or remotely from anywhere. You can also allow access to other users, and they will also need the ismartgate Access app. 

Additionally you can have an ismartgate camera that records* the open/close events to the ismartgate app (*this requires a video plugin)