No more option to create a web app ?

I'm trying to create a visualisation to plot a 3D scatter.

I saw that it is possible to create a web app to integrate d3 for exemple, as shown here : https://www.dataiku.com/learn/guide/code/webapps/adapt-a-d3-template.html and there : https://sonra.io/2016/03/15/plot-ly-in-dss-web-app/

However, I can't manage to find the "new webapp" button on the interface. Clicking on "new insight" pop up a windows with a "source web app" to select, but there's no web app selected and it doesn't seem to be any.

My question is, how do I create a web app ?