Look in the App store under Remote File Managers. They should let your access ROCK’s files from your iPad using the instructions linked to here or in @jamie’s post.
To access the Web GUI, hook a monitor up to the Nucleus. After it boots up, you will see an IP address. Enter that in a web browser.
Or you can try this in a web browser, but I’ve never had luck with that method.
If you can get into Settings==>About from a Remote, the IP will be displayed for your Nucleus. As directed here -