This is because the executing privileges of your file are lower. To combat this, try right clicking your file and clicking "Run as Administrator". This will allow it to do things that require higher system permissions.
Hope I helped!
I found this code here: Request UAC elevation from within a Python script?
import ctypes, sys
def is_admin():
try:
return ctypes.windll.shell32.IsUserAnAdmin()
except:
return False
if is_admin():
# Code of your program here
else:
# Re-run the program with admin rights
ctypes.windll.shell32.ShellExecuteW(None, "runas", sys.executable, " ".join(sys.argv), None, 1)
Put this into your code and you should be able to open a Win10 Store Application via Python.