According to the book, Kushner got Tillerson fired for a $50 million UAE payment because Tillerson supported Qatar. This panicked Qatar because they realized Kushner was a pay-to-play operative, so they bought Kushner's New York City apartments, which were in the red, hoping this would help.
This book is really damning for Kushner. It claims the UAE paid Kushner $50 million to get Rex Tillerson fired as Secretary of State.