Couldn't God have given us free will while also preventing evil? But we aren't omniscient. To answer such a question, we would have to know what God knows.
To illustrate how God might prevent free creatures from doing evil, Eleonore Stump says that God might cause dreams that vividly show the consequences of our evil deeds, but Jones responds,
“Would it have made much difference if a man or woman, or even thousands of men and women, had a smoking-is-dangerous dream? After all, printed on packages of cigarettes are alerts such as ‘SURGEON GENERAL’S WARNING: Smoking Causes Lung Cancer, Heart Disease, Emphysema, And May Complicate Pregnancy,’ but more than 40 million people still smoke in the USA.”
Study guide link:
 Clay Jones, Why Does God Allow Evil?: Compelling Answers for Life’s Toughest Questions (Eugene, OR: Harvest House, 2017), 134.