Best Path for 18 year old that did not get math fundamentals

I am a parent and joined 4 years ago. There is something called a mastery challenge that reinforces skills each time  you master the skills -- the one that generates your progress percentage - ie level 1 to mastered.   How do you get your students (like my child)  to access this each time they log on.   I thought this used to be automatic 4 years ago.  I think this is a really good way to build up your confidence showing you that you do know certain things even if it is just adding two numbers together.   Also is there is tour of Khan for the math area? I signed up 4 years ago and a lot has changed.   

My child is 18 now and always had a good mathematical sense, but did not learn the basic skills.  What is the best way for her to move through Khan.  

My child is taking grade 12 applied math but does not have the fundamentals, and does not respond well to parent intervention.  Is there a way to get another volunteer coach from Khan academy?