I'm on Windows10. I used the following:
C:\Users\mustf\AppData\Local\Programs\Python\Python37\Scripts>pip install beautifulsoup4 Requirement already satisfied: beautifulsoup4 in c:\users\mustf\appdata\local\programs\python\python37 (4.8.0) Requirement already satisfied: soupsieve>=1.2 in c:\users\mustf\appdata\local\programs\python\python37\lib\site-packages\soupsieve-1.9.4-py3.7.egg (from beautifulsoup4) (1.9.4)