Import yfinance as yf
The best way to install a python library is to:

Open a terminal or cmd or powershell on your system.
If using a virtual environment, activate the environment in your terminal or cmd or powershell.

For e.g., A virtual environment named virtual_environment created using virtualenv in C://Users/Admin/VirtualEnvironments/ directory can be activated by opening a terminal or cmd or powershell in that directory and running python -m virtualenv virtual_environment/Scripts/activate. For ubuntu users, python -m virtualenv virtual_environment/bin/activate.

To install a library named python-library, Run pip install python-library.
To install a specific version of that library, like a library named python-library with version 2.0.1 can be installed by Running the command pip install python-library==2.0.1

Similarly, you simply have to run pip install yfinance
If you want to install a specific version, like 0.1.70, then run command pip install yfinance==0.1.70.
If you have a .whl file of that library like python-library.whl, and want to install that wheel, then run command pip install python-library.whl.
Import yfinance as yf
Should run normally on conda but get this message

ModuleNotFoundError Traceback (most recent call
  last)  in 
        1 import pandas as pd
  ----> 2 import yfinance as yf
        3 import matplotlib.pyplot as plt
ModuleNotFoundError: No module named 'yfinance'

Strange? As should be simple to install?