I think the first time you installed the bootloader but not rockbox. The second time it looks like you installed rockbox but not the bootloader. You need to install both at the same time or its not going to work.
Actually, you need to install both, but if you only install the bootloader (what you did initially) you can install the main Rockbox binary without reinstalling the bootloader -- Rockbox will go into bootloader USB mode, and that can be used to put the remaining files on it.
That being said, I'm wondering if the Ipod you selected is actually the Ipod you have. Your 1st screenshot doesn't show any error, just the "normal" user interaction required to install the bootloader on the Ipod 6G. And if the computer isn't recognizing the Ipod properly I'd try (1) using a different USB cables, (2) using a different USB port, and (3) if Rockbox runs disable it's USB HID mode.
Also, if you're having issues with Rockbox Utility it much more helpful to post the system trace (Help / Troubleshooting / System Trace) than screenshots since it tells us a lot more.