Incorrect to the best of my knowledge. Advances in front of the top in the table, you've found, indicates that whoever finishes there will advance, ie. not necessarily who's placed there now.
They likely haven't agreed it as such, but the match will be a real pain. Many South American leagues are gamemanship from any side that has a result they deem good, no matter how far along the match is. Argentinian football is the absolute worst at it. If you, despite not being a football guy, happened to watch the Arsenal vs. Atletico semis, then think not one but likely two teams acting like Atletico, and worse actually, from minute 1. It'll be all rolling around with any tackle, taking 45 seceonds for every throw-in, misplacing the ball on purpose at corners etc. Anything's fair game.