The setting of God telling the soul information appears to be a literary device rather than an actual account of divine dictation–in other words, while the theology was her own, it was as much of an actual conversation with God as Dante had actual conversations with Virgil, St. Peter, and Thomas Aquinas in The Divine Comedy.
To my knowledge, she never asserted to anyone that it was an actual dialogue between her and God, though one is free to correct me on this point if I am wrong.
Catherine did claim other actual visions or experiences with God, however.