There are 3 preferred ways to install 
First you need to install sbt itself then you need to add the following dependency:
libraryDependencies += "org.specs2" %% "specs2-core" % "4.3.4" % "test"
scalacOptions in Test ++= Seq("-Yrangepos")See here to learn more about sbt dependencies.
You can install Maven from there. Once installed, you need to create a pom.xml file with the maven-scala-plugin. In the pom.xml file you can add the following dependency:
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  ...
<dependencies>
  <dependency>
    <groupId>org.specs2</groupId>
    <artifactId>specs2-core_2.12</artifactId>
    <version>4.3.4</version>
    <scope>test</scope>
  </dependency>
</dependencies>
  ...
</project>Go to this page to install Gradle. You then need to install the Scala plugin and add the following to your build.gradle file:
repositories {
  maven {
     url "https://oss.sonatype.org/content/repositories/releases"
  }
}
dependencies {
  testCompile "org.specs2:specs2-core_2.12:4.3.4"
}Depending on the 
| Name | Functionality | 
|---|---|
| specs2-matcher-extra | for the optional | 
| specs2-cats | for the cats matchers (only for cats < 0.8.x) | 
| specs2-scalaz | for the scalaz matchers ( TaskMatcherfor example) | 
| specs2-scalacheck | to use ScalaCheck properties in specifications | 
| specs2-mock | to use Mockito matchers | 
| specs2-analysis | to use the package dependencies matcher | 
| specs2-gwt | to write given/when/then specifications | 
| specs2-html | to export specifications as html | 
| specs2-form | to create html form-like specifications | 
| specs2-junit | to run specifications as JUnit tests | 
Note: the specs2-core jar depends on 2 other 
| Name | Functionality | 
|---|---|
| specs2-common | utility classes for text, collections, xml,… | 
| specs2-matcher | common |