Are you getting prompted for the location of the Scala install? What are you doing at the time? Do you have a project open at the time?
If you create/import a Gradle or SBT project, it shouldn't need the path to a local Scala installation, because those respective tools download Scala and invoke it. If it's prompting in that case, that sounds like a bug.
We will prompt for the Scala install location for single-file projects - that's the case where you don't have a project open, and you just open up a Scala source file. In that case we invoke "scalac" directly, and we need a path to an existing one. We don't currently download a compiler for you in that case.