For this book, you need R installed on your machine (or the machine you will be running scripts against). R is available for a number of platforms. This book is not constrained to particular versions of R at this time.
You need an interactive tool to develop R programs in order to use this book to its potential. The predominant tool is R Studio, a fully interactive, self-contained program available on several platforms, which allows you to enter R scripts, display data, and display graphical results. There is always the R command-line tool available with all installations of R.