These tools were purchased by Corel long time ago. After the purchase, Corel relesed them as Corel KPT collection. Nowadays, the filters are available in the Corel Painter application.
No, the default version of the tools is not compatible with the Windows 8.1. You will have to use the new application to enjoy them. Additionally, the tools from Painter are not available for Adobe Photoshop Elements.
Official website for Corel Painter: http://www.painterartist.com/us/product/paint-program/