If you are setting up a modern development environment, Microsoft recommends installing the .NET Framework 4.8 Developer Pack , as it is the last major version of .NET Framework and includes support for all previous versions (including 4.5) via multi-targeting.
.NET Framework 4.5 Developer Pack (which includes the Multi-Targeting Pack) is a critical resource for software developers who need to build or maintain applications targeting the .NET Framework 4.5 using Visual Studio. Essential Download Links While .NET Framework 4.5 has reached its End of Life net framework 45 developer pack link
Microsoft has consolidated many older developer packs. You can find the official installers through the or the .NET Download Archives . Official Archive: Download .NET Framework 4.5 If you are setting up a modern development