downloaded the TouchScript v9.0 unity package .

opened the package into Unity v2019.4.2f1 LTS .

open any of the example scenes.

click on TouchManager prefab at the scene and then click Select to locate the prefab in Project window.
from now on the unity is stuck in this status (I can only crash the entire project from Task Manager)

any other ways were not able to remake this response.
but this one happens every time.