Once Shaktipat occurs, enlightenment always follows. The only thing that varies is the speed at which the process unfolds, and this is based solely on your ability to surrender, your willingness to go along with the movement from mundane to universal consciousness.
Free will is never touched in this entire process. What you do after Shaktipat is up to you. In a way, it’s a kind of test: do you take the power and stay true to the path, or do you use the power to fulfill your base desires? After Shaktipat, enlightenment is inevitable, but if you make incorrect decisions, it will just complicate things for you and entangle you in more suffering.