Can't get "Creator Kit: RPG" to run

Hi everyone

I am quite new to Unity currently following the tutorial for the Creator Kit: RPG (here). I made sure my Unity is up to date, I downloaded and imported the assets, double clicked the scene "Sample Scene" but nothing shows in the window.

I also get three error messages without me modifying or adding/deleting any scripts. All three error messages come from the file `Assets/Creator Kit - RPG/Scripts/Tiles/Isometric Rule Tile/Editor/IsometricRuleTileEditor.cs`:

1. it complains that a class with that name already exists and yes, it does
2. the RuleMatrixOnGUI function has the wrong parameters (missing BoundsInt)
3. the RuleMatrixOnGUI and ContainsMousePosition functions have the wrong access modifiers (internal instead of public)

So it seems that the Creator Kit: RPG does not run out of the box? When I delete this problematic file IsometricRuleTileEditor (maybe it simply got integrated into core Unity?) then I get no more errors but the scene still doesn't show anything.

Or am I doing something wrong? What could I check? Can someone quickly test the default Creator Kit whether it works by itself?