You need to download the source code from the OP (instead of just the exe file) and edit these files:
Skillkeeper-master\SmashGGApiWrapper\Tournament.cs
SkillKeeper-master\SmashGGApiWrapper\Videogame.cs
in Tournament.cs, change this line:
public bool showCity { get; set; }
to:
public string showCity { get; set; }
in Videogame.cs, change this line:
public bool enabled { get; set; }
to:
public string enabled { get; set; }
then you need to build the solution. I used Visual Studio 2013 for this:
https://www.microsoft.com/en-us/download/details.aspx?id=44914
Once installed open the SkillKeeper.sln file with Visual Studio and then click Build -> Rebuild Solution. then click the "Start" button with the green play arrow and it should run.