I have been doing mobile electronics installations for better than 18 years. I can not say specifically that I have installed that particular model but if you follow these instructions it will work. I have installed many Scytek remote start/keyless entry pieces and although they are inexpensive I can say they work very well for many years if installed properly.
To wire up your trunk release, get a relay and wire it like this:
Pin 85: Gray Aux Output 1 from Astra 50
Pins 86 and 30: Constant +12V fused input
Pin 87: Output to trunk release wire in car (black/white wire at trunk release switch)
To activate the output you need to hold down the trunk release button on the remote for more than 2 seconds. It is purposely delayed to prevent accidental opening of the trunk.
If your car came with keyless entry from the factory, which I am assuming yours did not, you could hook the gray from the A50 directly to the brown at the trunk release relay to the left of the steering column.
Hope this helps.