Make sure you have the Forge Maven2 repository reference and dependency definition in the root pom.xml of your project.
    <repositories>
      <repository>
        <id>hippo-maven2-forge</id>
        <name>Hippo Maven 2 Forge Repository</name>
        <url>https://maven.onehippo.com/maven2-forge/</url>
      </repository>
    </repositories>
    <dependencyManagement>
      <dependencies>
        <!-- NOTE: You should set a property named 'bloomreach.forge.documenttranslationpicker.version' to a version of this plugin -->
        <!-- NOTE: before 5.0.0, the groupId was org.onehippo.forge -->
        <dependency>
          <groupId>org.bloomreach.forge.documenttranslationpicker</groupId>
          <artifactId>documenttranslationpicker-addon-repository</artifactId>
          <version>${bloomreach.forge.documenttranslationpicker.version}</version>
        </dependency>
        <dependency>
          <groupId>org.bloomreach.forge.documenttranslationpicker</groupId>
          <artifactId>documenttranslationpicker-addon-frontend</artifactId>
          <version>${bloomreach.forge.documenttranslationpicker.version}</version>
        </dependency>
      </dependencies>
    </dependencyManagement>
    Add the following dependency reference into your CMS dependencies module:
    <dependencies>
      <!-- NOTE: before 5.0.0, the groupId was org.onehippo.forge -->
      <dependency>
        <groupId>org.bloomreach.forge.documenttranslationpicker</groupId>
        <artifactId>documenttranslationpicker-addon-repository</artifactId>
      </dependency>
      <dependency>
        <groupId>org.bloomreach.forge.documenttranslationpicker</groupId>
        <artifactId>documenttranslationpicker-addon-frontend</artifactId>
      </dependency>
    </dependencies>
    
          The plugin contains a bootstrapping module with group "hippo-forge". Make sure your project bootstraps later
          than that, by setting after: [hippo-cms, hippo-forge] in the hcm-module.yaml file of the
          repository-data application module.
        
Now, rebuild, run and you're ready to use the plugin!