Everyone on Westworld has a slightly different motivation. Bernard wants to create the most perfect hosts. I imagine some engineers just want not to be fired. The hosts themselves are learning to deal with their trauma as they realize for the first time that it's happened. The newcomers are still trying to figure out what they want from this place. And the Man in Black's motivation is clearest of all. He's looking for the deeper level of the "game." Which is why he captures Lawrence to try and figure out where is the maze on Westworld. Lawrence's daughter gives in and gives him a clue, but it's not very clear.
After watching the Man in Black kill her parents, she tells him to "follow the blood arroyo to where the snake lays its eggs." Great, thanks so much. That was very clear. At least, the Man in Black seems satisfied. It's unlikely that the hosts are capable of saying anything that wasn't deliberately programmed into them, which is why when passing messages to each other, they have to rely on pre-programmed phrases, like Abernathy's Shakespeare quote, "These violent delights have violent ends." Some Westworld theorists believe that the blood arroyo and the snake eggs have roots in Shakespeare as well.
Redditor Aoibhneas draws a connection between Dr. Ford and Julius Caesar based on a soliloquy by Brutus in the Shakespeare play Julius Caesar, which is quite a scholarly analysis of Westworld, I have to say. Basically, in the soliloquy, Brutus claims that in his climb to greatness, Caesar forgot where he came from, and has lost his mind a little bit. He compares him to a snake still in the egg. "And therefore think him as a serpent's egg,/Which, hatch'd, would as his kind grow mischievous,/And kill him in the shell." It's harmless now, but it should be killed before it hatches and becomes dangerous. The Redditor believes that Ford is Caesar (basically), and that he is the beginning of the maze, or where the serpent lays its eggs. And as for the blood arroyo, well you may have noticed an interesting face tattoo on Armistice, the female gunslinger. It turns out that this tattoo is of a red snake, which wraps around her entire body. Like a stream. Which is English for "arroyo." Could the riddle mean that the Man in Black is to follow Armistice to Dr. Ford?
This theory has gained some favor. Another theory on Reddit posits that the maze is actually the Delos Mesa Hub, where all those engineers are working. This theory goes even further to hypothesize that the Delos employees are just evolved hosts who have become self-aware, and that Dr. Ford is the only non-robot among them.
In either case, the little girl also told the Man in Black "the maze is not meant for you." So there's guaranteed to be trouble when and if he does find it.