Manage to = succeed in doing something difficult.
Bob managed to get an A in vector calculus.
But it can also be used in a somewhat sarcastic way to mean that something is very difficult to mess up and yet you still do.
I somehow managed to lose my keys even though I tied them to my bag.
She managed to get an F in physical education. How is that possible?!
I somehow managed to shatter the screen of my phone even though it was in a very expensive case.
Does that help? I found this hard to explain.