Macilai joined the BNZ Crusaders in 2015, but a broken arm in a pre-season game meant his debut came later than expected. A knee injury also kept him from the field during the 2017 Super Rugby season, but he will be ready to make an impact in 2018.
Macilai learned his trade playing sevens rugby in Fiji. It was while playing for the Red Rocks Rugby Club in the Coral Coast Sevens competition in 2012 that he was spotted by Northland scouts and moved to New Zealand to play for the Awanui Rugby Club, helping them to win that year's club title.
He made his ITM Cup debut for Northland in 2013, although a dislocated elbow stymied that season. He spent some time training with the Blues wider training group in 2014 and his form in that year's provincial competition was impressive enough to grab Crusaders selectors' attention, and saw him gain the third highest number of clean breaks and metres gained of any player in the competition.