NuGetForUnity not working with .NET 4.x?

Hello dear Community,

I have a project where there have been .dll files used and stored in the "Plugins" folder. Now NugetForUnity has been installed to make the whole process of adding new packages easier. The issue is that one of the .dll's from before needed .NET 4.x or above to work. But NugetForUnity apparently needs .NET Standard 2.0 because when I want to build the project it tells me the following error message (upper picture): So I changed the API level to .NET Standard 2.0. Now I get the error for the other .dll (lower picture)

I then realized that the NugetForUnity.dll was in a folder called "Edito". I guess it was supposed to be called "Editor", so I renamed it. Now as anything placed into a "Editor" folder, unity ignores the NugetForUnity.dll on building the project and everything works fine. Nuget was not needed in the built project anyway because what would I need Nuget for anymore?

The thing that still makes me curious is "why didn't it work with the .dll in the "Edito" folder?" That the AMLEngine.dll might not have worked with .NET Standard 2.0 makes sense to me, since (accoring to the documentation https://docs.unity3d.com/2019.3/Documentation/Manual/dotnetProfileSupport.html) .NET Standard 2.0 has less librarys than .NET 4.x and some might have been needed for the .dll to work. But what does .NET Standard 2.0 has that .NET 4.x has not, so that nuget could not be included into the build?