What does "up to" mean here?
"Up to" in this context means to be lesser than or equal to something else, but not greater. "Up to" here is better understood as a part of the phrase "catch up to". To "catch up to" someone means to reach the level or the distance of someone who has gotten ahead of you, but not to surpass them. Ex: I have one more person to catch up to in the race. Ex: She has the highest grade in the class, no one has caught up to her yet.