What's the meaning of "scrambled up"?

Solution 1:

Scrambling is a verb meaning to climb over boulders or rough ground. It's like "climbing, but not as vertical", if you know what I mean,

https://www.merriam-webster.com/dictionary/scramble has it as:

1: the act or an instance of scrambling: such as
a: the act of moving or climbing over something quickly especially on all fours,
  eg "scramble over the boulders"

This professor is using it in the metaphorical sense, implying that his progression up the learning curve was not easy or smooth, and perhaps also a bit rushed, or not as under control as he would have liked.