The Qonic Desktop Application is designed to work in conjunction with the browser dashboard environment - it does not work as a completely standalone application at this moment. It is designed to be opened automatically from the dashboard if indicated by the user.
If you start the Qonic Client application from your desktop, it will instead open up your web browser on the page app.qonic.com/projects. From there you are able to open models, either in the web browser or in the desktop application.
If this message is not shown, head to My Account > Model Settings > Always open models in > Always ask or Desktop App, depending on your preference.
If this does not work as expected, make sure the latest version of the desktop app is installed. You can download the latest version of the desktop app at qonic.com/downloads. Note: if during installation a message appears that a more recent version of Qonic is already installed, that error message may be incorrect and you may need to uninstall that version first, before installing the latest version.