I think the two are separate abilities. When one does something from instinct, IMO one does the act without thinking about it. In other words, one is not contemplating a choice. Eg. If a child is about to put their hand on a hot stove top car, one would instinctively pull the child's hand out of the way. IMO each person's instinct could vary. Eg. When I see one of my kids playing on the playgym outside and perhaps their activity could lead to an accident, I might watch them for a moment to evaluate what they are doing before taking action, but someone else, for various reasons, may scream at the child immediately or rush out and grab them from the playgym.
instinct
n. 1. An inborn pattern of behavior that is characteristic of a species and is often a response to specific environmental stimuli: the spawning instinct in salmon; altruistic instincts in social animals.
2. A powerful motivation or impulse.
3. An innate capability or aptitude: an instinct for tact and diplomacy.
adj. 1. Deeply filled or imbued: words instinct with love.
2. Obsolete Impelled from within.
free will n. 1. The ability or discretion to choose; free choice: chose to remain behind of my own free will.
2. The power of making free choices that are unconstrained by external circumstances or by an agency such as fate or divine will.