Hi again,
We do not officially support CDH 5.7 yet and the issue is probably caused by its missing driver as we do not bundle it yet.
However, you could try choosing the CDH 5.5 driver instead. It should work with CDH 5.7.0, at least from our experience. We also intend to provide support for CDH 5.7 in the near future, so if you wait a few weeks/months, you should be able to work with your cluster with no problems.
Regards
Lukas