To get the PDF:
Run sp on the command line inside this directory.
This shows how to get grid typesetting. The idea is to set the grid height equal to the leading of the text size. When you start the text at the grid line, it will always be at a discrete grid row, so every text line is within a grid row.
To see the grid, change show-grid="no" to show-grid="yes" in the file layout.xml.
The font is free software (SIL font license). See https://github.com/georgd/EB-Garamond for more information.