South African Greg Minnaar showed his experience after a conservative qualifier to claim the win ahead of American Aaron Gwin and Great Britain's Danny Hart.
National champion Rupert Chapman (Bergamont Hayes Factory Team) was 33rd ahead of Bryn Dickerson 51, Wyn Masters (GT Factory Team) 59, Louis Hamilton 71, Brannigan 74 and Ed Masters 77.
MacDonald has moved into the top 20 on the World Cup standings after three rounds. He joined some 70 riders in a commemorative ride down the course on Sunday to honour former World Cup champion Steve Smith (Canada) who died in a motorbike accident recently.
National champion Alanna Columb finished 14th in the women's downhill and fellow Kiwi Veronique Sandler was 19th in the competition won by the incomparable Great Britain rider Rachel Atherton, who was 12 seconds faster than second placed Tracey Hannah (AUS).
The competition moves to Austria for the fourth round this weekend.