Unfortunately, the only application that still exists and has nRFTool in its name is the one hosted on the Github website. It's developed by Paulo Borges and it needs a different operating system in order to run.
You can check for details using the following link: https://github.com/pauloborges/nrftool
To download the contents of the directory, use the Download ZIP button. Everything you see on the page will be archived and delivered to you as a single ZIP.
Alternatively, ask your question to the website owners here: http://support.informer.com/?start&win