Macaulay finished the four-round tournament for the Eisenhower Trophy with an aggregate score of 8-under 282. He was the second-ranked individual behind Ricky Fowler of the United States. Fowler carded a final round 75 and finished 10-under for the tournament.
"It's an unbelievable feeling. I don't have a better word than that," Macaulay said.
Scotland started the final round four shots ahead of the United States and extended that lead in gusty conditions. Macaulay's teammates, Wallace Booth and Gavin Dear, carded 79 and 75, respectively, as Scotland finished with a four-round total of 560, 20-under for the tournament. Booth was the fourth-ranked individual with a 5-under total of 285.
Nick Taylor of Canada tied with Macaulay for second place in the individual standings at 8-under through four rounds. Danny Lee of New Zealand, the U.S. Amateur champion and the world's top-ranked amateur, shot an 11-over 84 Sunday to drop back to 37th place among individuals, 5-over for the championship.
Though each team has three players, only the best two scores in each round count toward the team total.
"We are very ecstatic and very emotional. I am a very patriotic person so I don't know what else to say," Scotland captain George Crawford said.
Fowler was again the best of the United States team, finishing the final round 3-over for an individual four-round total of 280, two shots better than Macaulay. Teammate Billy Horchel shot 77 on Sunday and Jamie Lovemark had 81 as the United States finished at 11-under 569.
Sweden finished third at 6-under 574 through four rounds, led by Jesper Kennegard, who was 1-under for the tournament. France and Italy tied for fourth place at 5-under.
A total of 195 players from 65 nations competed at the tournament on the par-73 Royal Adelaide course.