On MacOS - iMac I have installed a ROON license on the account for a long time:
I plugged in the new Nucleus serial number 54B203133B6B, connected to the obtained IP address and run the clean Operating System - Reinstall (that was a big mistake)
The Nucleus should come with the codecs included. Them being absent, even after a reinstall, often points to a hardware failure (SSD being the usual culprit).
That said, if you copied over the codecs, and you still don’t see them, you probably did it incorrectly. Can you take a screenshot of the Codecs folder on the Nucleus?
Edit: I see you’ve downloaded the i686 version. The docs clearly state you should get the amd64 package, even adding a direct download link for it. Try that instead
Did you purchase the Nucleus from a dealer or from Roon directly? If from a dealer, that would be the first support call to make. If from Roon, we may be able to help get some attention from support.
Return it to the dealer - the fact that there is no RoonServer folder showing in the Data directory indicates that the Nucleus definitely has a problem. See this thread for a similar report: