Question:
How do I view XPS files created by Win2PDF on Windows 10?

Answer:
New versions of Windows 10 no longer install an XPS Viewer, but Win2PDF includes a XPS viewer that also can convert XPS to PDF.

You can also manually add the Microsoft XPS viewer using the following steps:

From the Start menu, open Settings -> Apps & Features.  Click on the Optional Features link:

Click the "Add a feature" button:

Scroll down to "XPS Viewer":

Click "Install", and the XPS Viewer will be installed and associated with XPS files.