The easiest way to install AutoMan is to manage your application's build using sbt by creating a build.sbt file. This tutorial will explain how to do that, step-by-step. But if you already know how to use sbt, just add the following dependency to your libraryDependencies section.
"org.automanlang" %% "automan" % "1.4.2"
sbt will download an AutoMan JAR and store it locally on your machine, along with all of AutoMan's dependencies.