You can download Skilling's source code. You can verify that nothing untoward is happening.
Suppose, for example, that your university uses proprietary software running in the cloud. The software's owner could record student data, and sell it. You would have no way of knowing.
Skilling doesn't do that (in fact, Skilling sites are "walled gardens"). How can you tell? Because you can download the source code, and inspect it. You can analyze its network traffic. You can use a debugger to watch the code run, step-by-step. Even if you end up running Skilling in the cloud, you know what's happening.