"Cannot start compilation: the output path is not specified for module..."

You just have to go to your Module settings > Project and specify a "Project compiler output" and make your modules inherit from project. (For that go to Modules > Paths > Inherit project.

This did the trick for me.

You have to define a path in the "Project compiler output" field in

File > Project Structure... > Project > Project compiler output

This path will be used to store all project compilation results.