Catholics are free to believe that human beings physically and biologically evolved from primates. However Catholics must believe that God Himself is the author of the human soul as a special creation.
Pope Pius XII’s Humani Generis:
Teaching Authority of the Church does not forbid that, in conformity with the present state of human sciences and sacred theology, research and discussions, on the part of men experienced in both fields, take place with regard to the doctrine of evolution, in as far as it inquires into the origin of the human body as coming from pre-existent and living matter - for the Catholic faith obliges us to hold that souls are immediately created by God.
We cannot say: creation or evolution, inasmuch as these two things respond to two different realities. The story of the dust of the earth and the breath of God, which we just heard, does not in fact explain how human persons come to be but rather what they are. It explains their inmost origin and casts light on the project that they are. And, vice versa, the theory of evolution seeks to understand and describe biological developments. But in so doing it cannot explain where the ‘project’ of human persons comes from, nor their inner origin, nor their particular nature. To that extent we are faced here with two complementary—rather than mutually exclusive—realities.
— Cardinal Ratzinger, In the Beginning: A Catholic Understanding of the Story of Creation and the Fall (Eerdmans, 1995), p. 50.
As to how this all played out, that is not something the Church has pronounced on…