The project Assembly-Csharp cannot be started directly

Hello, I created my project in Unity 5.3 using Visual Studio, I can play it in editor without problems. Now I tried to build it into Windows Store Application, since it is supposed to be a mobile game. I tried doing it according to this tutorial: https://channel9.msdn.com/blogs/shahedC/Publish-a-Windows-10-Game-with-Unity-5 These are my build settings:

Builds into a folder, and creates the solution. When I go into the solution, in the solution explorer it shows the solution as 3 projects.

I get 1 error and 163 warnings, some of them about obsolete components and that's fine for now, and some worse ones when debugging.

When trying to Build as x64 it doesn't build and the error is:

Could not copy the file "C:\Users\User1\Desktop\Game\UWP\Assembly-CSharp-firstpass\bin\x64\Debug\Unprocessed\Assembly-CSharp-firstpass.dll" because it was not found. C:\Users\User1\Desktop\Windows Store XAML Build\Game\Game.csproj 252
Also, that processor architecture of my project doesn't match the processor architecture of Assembly-Csharp project.

When trying to build as ARM or x86 it doesn't build and the error is:

(Error) Cannot find type System.SystemException in module CommonLanguageRuntimeLibrary

In both cases it throws back warnings, some of them like these:

(Warning) Failed to resolve all project references for 'Game'. The package restore result for 'Game' may be incomplete.

(Warning) The referenced component 'System.Core' could not be found.
(Warning) The referenced component 'mscorlib' could not be found.

And when pressing the green arrow with "Start" by it, it shows: The project "Assembly-Csharp" cannot be started directly.

How to get rid of this? I do have WIN10 SDK installed, and .NetFrameworks as well. Also, my project.json file: