error in using pyvol

[zhanr21]

I try to install pyvol based on instruction shown in here: https://schlessinger-lab.github.io/pyvol/install.html#:~:text=Download%20the%20basic%20GUI%20installer,PyVOL%20and%20any%20missing%20dependencies.
When I click pyvol in pulgin, it shows this error msg.
I am using windows 10 and pymol version is 2.0+
Could anyone help?

Error msg:
Traceback (most recent call last):
File "C:\Users\zhanr21\AppData\Local\pymol\lib\site-packages\pmg_tk\startup\pyvol_gui_init_.py", line 68, in pyvol_window
refresh_installation_status(form)
File "C:\Users\zhanr21\AppData\Local\pymol\lib\site-packages\pmg_tk\startup\pyvol_gui_init_.py", line 260, in refresh_installation_status
all_pckgs = subprocess.check_output([sys.executable, "-m", "pip", "list", "--format=json"]).decode('utf-8').strip()
File "C:\Users\zhanr21\AppData\Local\pymol\lib\subprocess.py", line 411, in check_output
**kwargs).stdout
File "C:\Users\zhanr21\AppData\Local\pymol\lib\subprocess.py", line 512, in run
output=stdout, stderr=stderr)
subprocess.CalledProcessError: Command '['C:\Users\zhanr21\AppData\Local\pymol\pythonw.exe', '-m', 'pip', 'list', '--format=json']' returned non-zero exit status 120.
Traceback (most recent call last):
File "C:\Users\zhanr21\AppData\Local\pymol\lib\site-packages\pmg_tk\startup\pyvol_gui_init_.py", line 68, in pyvol_window
refresh_installation_status(form)
File "C:\Users\zhanr21\AppData\Local\pymol\lib\site-packages\pmg_tk\startup\pyvol_gui_init_.py", line 260, in refresh_installation_status
all_pckgs = subprocess.check_output([sys.executable, "-m", "pip", "list", "--format=json"]).decode('utf-8').strip()
File "C:\Users\zhanr21\AppData\Local\pymol\lib\subprocess.py", line 411, in check_output
**kwargs).stdout
File "C:\Users\zhanr21\AppData\Local\pymol\lib\subprocess.py", line 512, in run
output=stdout, stderr=stderr)
subprocess.CalledProcessError: Command '['C:\Users\zhanr21\AppData\Local\pymol\pythonw.exe', '-m', 'pip', 'list', '--format=json']' returned non-zero exit status 120.
Traceback (most recent call last):
File "C:\Users\zhanr21\AppData\Local\pymol\lib\site-packages\pmg_tk\startup\pyvol_gui_init_.py", line 68, in pyvol_window
refresh_installation_status(form)
File "C:\Users\zhanr21\AppData\Local\pymol\lib\site-packages\pmg_tk\startup\pyvol_gui_init_.py", line 260, in refresh_installation_status
all_pckgs = subprocess.check_output([sys.executable, "-m", "pip", "list", "--format=json"]).decode('utf-8').strip()
File "C:\Users\zhanr21\AppData\Local\pymol\lib\subprocess.py", line 411, in check_output
**kwargs).stdout
File "C:\Users\zhanr21\AppData\Local\pymol\lib\subprocess.py", line 512, in run
output=stdout, stderr=stderr)
subprocess.CalledProcessError: Command '['C:\Users\zhanr21\AppData\Local\pymol\pythonw.exe', '-m', 'pip', 'list', '--format=json']' returned non-zero exit status 120.
Traceback (most recent call last):
File "C:\Users\zhanr21\AppData\Local\pymol\lib\site-packages\pmg_tk\startup\pyvol_gui_init_.py", line 68, in pyvol_window
refresh_installation_status(form)
File "C:\Users\zhanr21\AppData\Local\pymol\lib\site-packages\pmg_tk\startup\pyvol_gui_init_.py", line 260, in refresh_installation_status
all_pckgs = subprocess.check_output([sys.executable, "-m", "pip", "list", "--format=json"]).decode('utf-8').strip()
File "C:\Users\zhanr21\AppData\Local\pymol\lib\subprocess.py", line 411, in check_output
**kwargs).stdout
File "C:\Users\zhanr21\AppData\Local\pymol\lib\subprocess.py", line 512, in run
output=stdout, stderr=stderr)
subprocess.CalledProcessError: Command '['C:\Users\zhanr21\AppData\Local\pymol\pythonw.exe', '-m', 'pip', 'list', '--format=json']' returned non-zero exit status 120.