What I found was once you can see the e-Licence in the eLCC you need to activate it using the code that Steinberg sent to you via e-Mail, as part of the download. It’'s in plain font.
Steinberg, please put a search on your main .net website and have this in the FAQs.
To be honest we all expect exporting to MP3 to be part of the standard suite of tools in Wavelab Elements, or others. So please make this is easy to find (purchase plus instructions) as possible.