yes that was it.
Do I have to understand this?
by user 367081956959322114
The code in the samples is put into npmdef files so it can be easily added to other projects. You can read a bit about it here: Project Structure | Needle Engine Documentation
Think AssemblyDefinition files but for the web (behind the scenes those are just npm packages added to your project dependencies like any other npm package - npmdef is our integration of that into Unity)