First i spent 2 hours trying to install the demo version of Nina with J4. Everytime I got duplicate entry error when installing the database. Then I tried the J3 version with demo content, no success in creating the database. The window simply stuck. Several hours deleting database, reinstalling the database, trying from scratch on. Everytime same problem.

Then I gave it to a partner and asked him to try it.
He wrote:
With the 4 version the database recovery was faulty - some duplicate key - with a lot of searching I could fix it by hand after hours. Experience has shown that something does not work. With the 3 version I had the same error as you, after entering the database data, the page was called up and I got no further. It was only then possible with a fresh 3 version and installing the template. For the 4 version there was no template to install, although the folder was there.

So I want my money back for at least the J4 version.