You’re better off seeking answers for your rockon problems.
Rockstor thinks that it’s the default method for working with docker containers. Even if you found a way to install DockSTARTer alongside Rockstor, you’ll just end up with issues when these two things conflict.
It’s not a viable option to try and replace 1 part of the Rockstor appliance’s functionality.
Unless you want to fork the repository, pull the Rockstor code apart, kill the references and hooks to Docker and run your own complete custom installation, this is not a good idea, and it’s just not going to work.