I've moved your question to the Developer forum, since the LibDev Toolkit is only available to developers.
Which version of the LibDev Toolkit are you trying to install? If you unzip the file, you'll see mostly platform independent things - documentation, sources, etc. Under the Tool folder you'll find OS X and Windows version of the XML converter as well as documentation for it. There is nothing to install, just run as documented.
AC 28 USA and earlier • macOS Sequoia 15.4, MacBook Pro M2 Max 12CPU/30GPU cores, 32GB