In-Process NuGet don't support authentication. It should support obtaining credentials just like nuget.exe

Hints:
https://github.com/NuGet/NuGet.Client/tree/dev/src/NuGet.Clients/NuGet.Credentials
https://www.nuget.org/packages/NuGet.Credentials/