Thank you for trying our new platform and for your feedback.
Your issue is due to the fact that the studio was not yet available. Our team was notified and is currently working on resolving this issue so you can have the best user experience.
For the meantime you should be able to access to the studio by waiting for a few seconds and clicking on the studio button again.
We will keep you updated as soon as this issue is fixed.
Creating apps will be possible later on. At this stage of the beta, you only get a sandbox. If you want to play with another demo (app template), you can safely delete your sandbox and create a new one. Then you can select another demo.