Visual Studio - "The environment IronPython|2.7-32 appears to be incorrectly configured or missing"

You need to set up the IronPython 2.7 environment*.
^{*Currently you cannot do it through the Visual Studio Installer (there isn't an IronPython Package option to install).}

1. You need to download IronPython and install it separately from Github.
2. After it's installed, you need to select the correct python environment within your VS project.
3. If the IronPython 2.7 environment is not properly set then you have to do it manually

Hopefully, Microsoft will patch this in the future.