The native file format for Live 3D CX is .xmm, or Master Model. The .xmm file is actually a ZIP-style file archive, with a different extension (.xmm vs .zip.)
To access this content, unzip it to a folder on your machine, and then just open the main HTML file, typically named index.html.
If you do this, and see an essentially blank page, with a small icon where the Strata Live 3D content is supposed to be, you are probably running into a security feature of Windows. Using your file explorer, right-click the HTML file, and choose Properties. At the bottom, you may see a message that says:
This file came from another computer and might be blocked to help protect this computer.
Click the Unblock button, then OK. This will allow the content to run on your computer.