Hi Raphael,
> Is it possible to make a dashboard, with a free license here, arcgisonline? Or just webmaps?
No, an ArcGIS Online public account (that is free) will not allow you to create dashboards. As you said, it only allows you to create web maps and you can access some of the ArcGIS configurable app templates. You will need an ArcGIS Online organizational account to use ArcGIS Dashboards.
Hope this helps,
