The 20-year-old Goya started the day three shots ahead and closed with a 2-over 73 to finish at 6-under 278. Macaulay, ranked No. 1,009, equaled a course record with a 64 in which he birdied eight of the last nine holes.
Goya, who won the Tour de Las Americas Order of Merit last year, began the final round at the Seve Ballesteros-designed course with a birdie at the first hole. He double-bogeyed the third hole and then birdied the sixth.
Goya dropped another shot at the 13th but birdied the following hole. However, his double bogey on the 16th made for a tense finish. The Argentine parred the 17th and 18th for the victory.
Wil Besseling of the Netherlands and Damien McGrane of Ireland were next at 280. Anthony Wall of England was at 281, a shot ahead of Northern Irelands Michael Hoey, who led after two rounds.