The standalone plugin is no longer actively developed as a free forever tool. However, you can access its core features for free via the PixelSquid website or through their CC Library integration (which requires a free account).
If you want to use PixelSquid 3D assets in your design work safely and effectively, you should abandon the plugin route and use the standard workflow. This is the professional ("proper") method used by designers today: pixelsquid photoshop plugin free download
If you want a for 3D objects, try:
All materials on the site are presented solely for information. All trademarks and copyrights in the published materials belong to their respective owners.