Google Calendar -> Home Assistant - Node Red

I try to integrate Google Calendar into Home Assistant using embedded Node red and the node-red-node-google integration. I have created a Google Dev according description and added the client ID and secret as required.
I also added Redirect URIs of your app to include the following url:
and the

Configuration according node-red-contrib-google-oauth2 (node) - Node-RED for Java script sources. I used here the same link as above wihtout the api.... stuff.

Now i try to Authenticate. Google is called, i check the google calendar using my google account. But after pressing OK i get an error 401: unauthorized.

HA is attached behind a Fritz box router and i use duckdns to route the https call to the fritz box and from there to the correct port of the HA instance. Accessing the HA from outside via HTTPS is working fine.

Not sure what the issues is.