Hi Dimitris,
Sorry to see this happens on your machine. First, can you try to check if your machine meets the system requirements? Then, if this issue still happens, please feel free to send us your error log, so that we can help locate the problem. To do so, you can go to your local workspace directory, with default installation process, the error log folder should be under C:\Users\username\AppData\Roaming\ESRI\ArcGISEarth\, named logs.
Another way worth trying is to clean up the workspace (ArcGISEarth) folder and try launch again. Thanks!