The primary official resource for all .NET Framework versions is the Microsoft Learn installation guide, which provides links for installing all versions of .NET Framework from 4.5 to 4.8.1:

Here is the direct download link and what you need to know about installing it.

C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.5

Open the application on your machine.

Finding a direct download link for the .NET Framework 4.5 Developer Pack can be challenging because Microsoft no longer provides a standalone download for this version due to its end-of-support status. However, here are your best options:

This public link is valid for 7 days and shares a thread, including any personal information you added. This link or copies made by others cannot be deleted. If you share with third parties, their policies apply. Can’t copy the link right now. Try again later.