The Java+ analyser is triggered when one of the relevant manifest files (“pom.xml”, “build.gradle”, “build.sbt”) is found in the root of the project.
When using Maven. Gradle or Sbt, the tool will be actually invoked to generate the dependencies tree, as it's the only one who actually knows the components that, at the end of the day, will be really shipped. If you rely solely on the manifest files you will have to replicate what the tool is doing, which is really unreliable. The logic used is frequently just too convoluted, and only if you ask the tool to generate the dependencies tree you will be obtaining the right one.
For that reason, your project has to build successfully before using Meterian. If this condition is not met then you won't be able to use this tool, so please make sure the project you want to attack is compiling correctly.