You can download this whole repository from the Releases tab, but it won't include the true data. For that, you'll need to download the following:
- ArcGIS (10.x): https://github.com/nickrsan/Python-GIS-Field-Calculations/raw/master/arcgis/field_calculator_2019.mpk (open this wherever you like)
- QGIS (3.x): https://github.com/nickrsan/Python-GIS-Field-Calculations/raw/master/qgis/field_calculator.gpkg (put this in the QGIS subfolder of the downloaded repository). The
.qgz
map file is from QGIS 3.4, but the data will work in any QGIS version that supports GeoPackages.