Reconciling Divine Decree with free will is one of the biggest challenges within the Abrahamic traditions. The explanation that I offer below is a very concise, extremely simplified version of the popular Islamic view, consistent with what is called the Ashari Creed. (Another similar thread focusing on Christian views on this same issue can be found here.)
Divine Decree and free will
God knows all that was, is and will be, and God exists independently of time, but created time and wills things to take place chronologically. He knows what choices people will make, and He decides whether or not to facilitate these choices. People have their own wills (free will), but God decides (determines) whether or not what people intend will actually come to pass, and thus His will is done.
In summary, from Learndeen:
BELIEF IN GOD'S POWER IS BASED ON FOUR THINGS:
1 – العلم Knowledge: i.e., that God knows what His creation will do, by virtue of His eternal knowledge, including their choices that will take place.
2 – كتابة Writing: i.e., that God has written every thing that exists including the destiny of all creatures in the preserved tablet prior to creation.
3 – مشيئة Will: i.e., that what God wills happens and what He does not will does not happen. There is no movement in the heavens or on earth but it happens by His will. This does not mean that he forces things to happen the way they happen in the area of human beings volunteer actions. It means that He knew what they will choose, wrote it and let it happen, was and is always able to change it when He wants.
4 - الخلق Creation and formation: i.e., that God is the Creator of all things, including the actions of His creation. They do their actions in a real sense, and God is the Creator of them and of their actions.
Note that God is a multi-dimensional entity, and while our wills exist within the three/four dimensional world, God's will transcends it. See Mokhtar Maghraoui - Pre-destination & Divine Decree - Part 1 of 5.