Access Linux Platform container from the Mac OS X plan

I see in my projects Settings -> Overview that I have OS X Plan with 1 free Linux container, but I can’t figure out how to access that container.

We have a monorepo and when I try to SSH into a build on master, I see it’s the Mac image (that is, there’s no $ANDROID_HOME). There also seems to be no Maven. Additionally, the I can’t set up the Java 8 version in the circle.yml.

I also can’t seem to turn on parallelism from the build dashboard. It redirects me and says that it’s not possible on an OS X plan, which I’m guessing is the mechanism running in another container.

Any help would be appreciated!