You can the calendar that comes with the Soverin account with a CalDAV compatible client. The Apple Calendar Application found on a Mac (or the App on iOS devices) is compatible with this protocol. Below you'll find the instructions to configure the Application found on a Mac.
- Open the Calendar Application and go to the preferences (Calendar ➔ Preferences) / Hotkey Cmd-,
- Go to the "Accounts" Tab and hit the "+" underneath the account list
- Select "Other CalDAV Account....
- Fill in the details found in the dashboard
Your account should be added automagically.