You will need Scala and SBT installed on your system. Technically, you only need SBT, since SBT will install the required version of Scala for you. You can get Scala and SBT from the following websites:
It is advisable that you use a UNIX-like operating system for this book. However, this is not strictly necessary for most chapters. You will also need a Scala IDE or a text editor. Setting up Emacs to work with Scala and SBT is covered in the book. Alternatively, you can use any editor you are comfortable with.