You should be able to download all the versions. Go to the appstore and click on Business modeller. At the right hand side of the page that opens you see the option other versions. There you could download the latest stable release.
Furthermore you need to create a user in your app. I assume you try to log in with your Mx ID. You should first try to log in as MxAdmin with the password that you can set in the model. And try to view tutorials at https://gettingstarted.mendixcloud.com
Thank you for your answer, something happens from Mendix back-office, now app-store can be used (before i had an error the error of no MxId account) maybe i was to be granted. Thank you for your guidelines now that is working i would continue downloading the previous stable version, strange that in the getting started the link point to a beta version. I'm getting trough all the lesson very fast...looks always easy in the beginning...
You can change state to Resolved or i have to do this?