There are multiple Python environments are available on AWS Marketplace Windows Server image for ArcGIS. Portal, Pro, and Server in the screenshot below have Python.

Step-by-step guide

If you activated ArcGIS Pro, you need to use the python under Pro/ directory to avoid license error.

  1. cd bin/Python/envs/arcgispro-py3/
  2. Run .\python <your_script>

Here's the typical error that you will encounter when the wrong Python was used.

 File "c:\Program Files\ArcGIS\Server\framework\runtime\ArcGIS\bin\Python\envs\arcgispro-py3\lib\site-packages\arcgisscripting\", line 119, in <module>
    from ._arcgisscripting import *
RuntimeError: The software is not authorized for use.