proj is a generic coordinate transformation software, that transforms coordinates from one coordinate reference system (CRS) to another. This includes cartographic projections as well as geodetic transformations. For datum grids, install the proj-data package. Without this package, proj can fetch required grids from the internet as needed. By default, the script does not build nor run the tests. You can use the option TESTBUILD=YES to build and run the tests before the make install part.