Have you completed Winston quest first ? Talk to him and complete his quest and it should unlock Betty quest line.
If you’re looking at the trailblazer guide, make sure you look at the pre-requisite for the quests which can be found at the top of each bbb page. The trailblazer guide can be found here: https://forums.maplesaga.com/index.php?threads/trailblazer-quests.22065/ gooseluck!