If downloading a full ISO isn't feasible, the file is often shared online. While these may be convenient, always verify the file against a trusted source. Some known locations include repositories on GitHub, links from IT professionals sharing verified files, and various tech forums and blog posts.
You do not need to buy a separate "package"; you can extract it for free from a Windows ISO Salesforce Locate the file: microsoft-windows-netfx3-ondemand-package.cab \sources\sxs\ folder of your Windows media. Execute via DISM: microsoftwindowsnetfx3ondemandpackagecab extra free