Hi Ujaval,
Do you mean the nuget packages are not installed automatically when you open the project in Visual Studio 2015 Community?
Please enable "Allow NuGet to download missing packages" and "Automatically check for missing packages during build in Visual Studio" in menu Tools -> Options -> NuGet Package Manager -> General.
And also check whether the Packages Sources is correct as below image shows.

If has enabled automatically install and the package source is correct but the package still not install automatically, please try install manually to check whether there has any error message when install that packages.
In addition, please check the NuGet packages that installed, whether they have corresponding version for Visual Studio 2015.
Best Regards,
Weiwei