I was able to install the app, but not able to access a learning lab public course as a member of an organization. I did successfully with a personal repo.
If I read the docs correctly, it looks like private labs to an organization are available to members of the organization. So, making my own labs will work internally in an organization. However, I cannot directly take a public lab and select it/assign it as a classroom assignment.
Has anybody tried GitHub Learning Lab? I like the tool, I showed do some of my students and it was very contagious, we all started doing the labs