PIA does not provide support for Windows XP, Windows Vista, Windows 7, or Windows 8. These operating systems no longer receive security updates from Microsoft and are no longer considered secure for general use.
If you still want to use PIA, you can use OpenVPN instead of the PIA app. OpenVPN Connect is a free, open-source application that supports connections to PIA servers. For setup instructions, refer to the OpenVPN setup guide for Windows.