That strike says " your visitors will be able to push or pull the door open when power is applied." That seems to mean it unlocks when you apply power.
You will need a transistor to switch the 200 mA power. Most any NPN transistor will do. Connect +12V from you power supply to one side of the strike. Connect the other side of the strike to the Collector of the transistor. Connect the Emitter of the transistor to both the - side of the power supply and your Arduino ground. Connect your digital output pin through a 1K resistor to the Base of the transistor. Turning on the digital output pin will power the strike and allow the door to open.