nwf to mp3 conversion is probably related to export of Nero WaveEditor project files (.nwf) to MP3 format, something that is very well only possible with the original software. The tools is used for audio edits, so export of the project is likely to produce altered version of the original store in the project.
As always, if you struggle with this export or need further assistance, it might be best to reach out to Nero support.
Updated: September 25, 2023