I have serious problems getting Lean to work on Visual Studio 2019 (Windows 10)

Among other errors, I still get the following even though I have already installed Net:

Errore        gli assembly di riferimento per .NETFramework,Version=v4.0 non sono stati trovati (not found). Per risolvere il problema, installare Developer Pack (SDK/Targeting Pack) per questa versione del framework o ridestinare l'applicazione. È possibile scaricare .NET Framework Developer Pack all'indirizzo https://aka.ms/msbuild/developerpacks    prova    C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\MSBuild\Current\Bin\Microsoft.Common.CurrentVersion.targets    1177    

Moreover: I have followed the tutorial on github for installation, but cannot figure out how to deal with Nuget (if I have to). If some of you could just tell me some very simple steps to try install Lean properly, i would be very grateful.  If I missed any fundamental information, just inform me and I'll be updating the discussion.

thank you