It depends if the angels are acting on God’s orders or they are in fact disguised demonic angels.
From the little I read in the excerpt it doesn’t sound like she conjures them up, she sees them around her. If she was using a ouija board or doing something to bring them to her, that would definitely be occultism. But if she’s seen angels all her life and she’s done nothing to make them appear, and can just see them, then it doesn’t appear to be her dabbling in the occult.
What is the purpose of God sending angels to us?
It certainly not for the reasons she writes about.
“Byrne’s story begins with the telling of her toddler years, when the angels told her that her tiny playmate was the brother who had died before she was born. “
I’m sorry this is not the work of the Lord!