The is the crucial component for developers. It contains the reference assemblies (the DLL files) that Visual Studio uses when you compile your code. Without the Targeting Pack, Visual Studio doesn't know what APIs are available in version 4.5, and your build will fail.
You should never download .NET Framework components from third-party “DLL download” websites. They often contain malware or outdated/corrupt files. Always use Microsoft’s official channels. net framework 45 developer pack link
Check the physical location: