You can sync PrivateMail Calendars on any Android device with the Open Sync app and CalDAV.
To Sync your PrivateMail calendar on Android using Open Sync first download the free Open Sync app.
Start the Open Sync sync app and tap the plus icon to Add an account:
Select "Login with URL and username". Enter in the PrivateMail CalDAV server URL and user/pass information:
Username: PrivateMail.com email username
Password: PrivateMail.com email password
You should now see the user profile added to OpenSync. Tap the user profile to select what Calendar options to sync.
Select the Calendar items you wish to sync with the Android device.