Running Scratch 2.0 files online is not currently available at the moment - due to the EOL of Flash, Flash files can only be run in browsers via Flash emulators. Currently, only the technology to run ActionScript 1 and 2 exists, and Scratch 2.0 was built using ActionScript 3. In order to try out Scratch 2.0 versions at this time, you'll need to download this Flash file and run it using Adobe Projector. I will add the ability to run Scratch 2.0 versions online as soon as it is possible.