Alternative to install arduino-esp32 for Arduino IDE (Windows)

B:\
   ->Arduino-Dev\
     ->hardware\
       ->espressif\

You need to replace B:\Arduino-Dev with your sketchbook location.
Then use git bash instead of the git GUI.

cd <your_sketchbook_location>
mkdir hardware
cd hardware
mkdir espressif
cd espressif
git clone https://github.com/espressif/arduino-esp32.git ./esp32

after cloning is finished do

cd esp32
git submodule update --init --recursive
cd tools
./get.exe

That should install the stuff in the correct place.
Important is to get the correct sketchbook folder from your Arduino-IDE preferences!