Goals from Khuliso Mudau, Brayan Leon and Iqraam Rayners ensured the South African champions took a strong advantage into the return leg.
VAR, which is introduced from the quarter-final stage of the competition, played a significant role during the match as Sundowns had two goals initially ruled out by the referee but later awarded after review.
Speaking after the match, Cardoso said the technology was important in assisting match officials, especially given the speed and pressure of the modern game.
"Absolutely, unfortunately we had Thapelo Morena injured in the situation in the last match, it was a red-card, it was not given. We saw in the last match here two situations that were taken from us or none existence of VAR," the Downs mentor told SABC Sport.
"Referees should be helped, the game becomes too quick nowadays, too much pressure, they need help and this is a fantastic instrument to help the referees."
Cardoso emphasised that his comments were not intended as criticism of referees but rather support for tools that can improve decision-making.
"Nothing against the referees, just supporting them so that they become better like we because we also for videos.
"Everybody needs to get better and get help in the support so yes important of course."
The result puts Sundowns in a strong position ahead of the second leg as they continue their pursuit of continental success in Africa's premier club competition.