In particular, the study says:
when considering deforestation, we find a near system-wide transition of the Amazon forest (62−77% of the area) under the combination of a lower threshold range of global warming of 1.5–1.9 °C and deforestation of 22–28%
The press-release is rather a bit clearer about it than the NYT
Around two-thirds of the Amazon rainforest could shift into degraded forest or savannah-like ecosystems at 1.5-1.9°C of global warming if deforestation increases to roughly 22-28 percent of the Amazon