Proving Ground have discontinued Lunchbox for Dynamo so there is only the code available now on Bitbucket (per your link) so it would need to be built from source to get the whole package. There is a related discussion here: Lunchbox package for revit 2021
However, if you are after a particular node then it is probably easier to look at the surce code to understand the logic to recreate the node either with OOTB nodes, Python or even ZeroTouch. For example the node in the original question Curves.DeconstructPolyCurve can be seen in the Zero Touch nodes section of the repository.
/// <summary>
/// Get segment and vertices of a polycurve
/// </summary>
/// <param name="polycurve">PolyCurve</param>
/// <returns name="Segments">PolyCurve segments.</returns>
/// <returns name="Points">Points at PolyCurve discontinuities.</returns>
/// <search>lunchbox,polycurve</search>
[MultiReturn(new[] { "Segments", "Points" })]
public static Dictionary<string, object> DeconstructPolyCurve(PolyCurve polycurve)
{
Curve[] curves = polycurve.Curves();
List<Point> points = new List<Point>();
foreach (Curve c in curves)
{
points.Add(c.StartPoint);
}
return new Dictionary<string, object>
{
{"Segments", curves},
{"Points", points}
};
}
Which can easily be recreated using the OOTB nodes PolyCurve.Curves and Curve.StartPoint
