arduino - Circuit Design to Power the ADH8066 GSM Module

I am struggling to find the proper circuit design layout to properly power the ADH8066 GSM module and communicate with my Arduino.

The ADH8066 requires a 4V power supply and can have a brief spike of up to 2A during the start of communication.

I have been able to use an adjustable voltage regulator to provide a clean 4V from my power supply, but I have been informed on a forum that I must also use capacitors to cover the amperage spikes (since the Arduino cannot permit that high of amperage to be pulled, even if the power supply supports that rating).

I am a new entrant into the EE space, so I am trying to determine the ideal capacitors to purchase and where they need to be introduced into my circuit.

If anyone has had experience getting the ADH8066 to operate (even if they have a different circuit design than I'm referencing above), any insight into the proper layout would be immensely helpful.