OH3 UI: Google calendar web frame

I am quite a newbie on OH3 and I am fiddeling around with the openHAB 3 UI.

I quite like the compact calender item view of my Google calendar, which also includes birthdays and my wife’s calendar entries, and I easily managed to get it into the view with a web frame card:

In the browser, with a valid Google session, it works perfectly fine, but in the app, without any session, it appears empty:

Is there a way to log in to Google to get the right view in the application or will I have to import every single calenders’ items with iCal?

Thanks in advance for any hint.