This was the answer. Thank you 
(I thought I had installed 3.12, but it was still using 3.8.
Maybe someone else will find this thread and find it helpful.
@carltongibson. Where do you prefer I post “how do I…”-questions about using Neapolitan? Thank you for a great package. It will save me heaps of time.
Just to try it out i added an extra model and copy-pasted a few lines of code in admin.py and urls.py and the new functioning model-CRUD was flying. This is great!