Luke is talking about his git repository on GitHub
see here in a web browser
do you know how to download with git?
If not you can download a zip of his code from the URL above. To do this first change to Luke's sketchDatum branch, then click the download repository as a zip file button which is labelled "zip" on the left of where the URL is shown in the web page above, (at github).
I assume you can compile FreeCAD from source? This above will get you the source code which you will have to compile, not a binary file or installer etc..
Luke has a few branches there, make sure you download the correct branch.