Are you preparing to use VS code for the first time? Just make sure you have enough privileges.
Have you defined your Iris server in your VS Code settings, and still get the following error?
VS Code accesses Iris/HealthConnect using the web application /api/atelier. If you do not have permission (i.e. you are using an LDAP user to connect and the web application is not configured to support LDAP), this is the reason why you couldn't connect.