Hume believes that humans don’t possess absolute free will. He believes that the regularity of natural laws dictates humans are predisposed do given an exact circumstance (given an event, the person’s psychological make up, knowledge, preferences, etc).
This does not mean that humans are not free, however. Hume argues that humans have the so-called hypothetical freedom, the ability to act according to their own psychological makeup and preferences, etc. As such, the idea hypothetical freedom explains the agent’s action and render them morally responsible.