For security reasons we do not allow access to admin panel from the demo website. Demo website is to be used for demonstration purposes so other users can see what a general website looks like.
If we gave admin panel access to public on demo website then anyone could change how it looks like or significantly alter its behavior which could confuse other users seeing the demo.
Once you subscribe to free trial or to any of our other plans you will get full access to the administration panel for your own website. Note that you can still however try the campaign creation and other features on our demo website.