OK, so in my case, i have followed these instructions Google Calendars - Home Assistant
Got my Client ID, Client Secret from google and all the neccessary settings done.
Then in HA went on settings – device & services – add integration – google calendar
After some time of Please wait while Google Calendars is being setup, I get the message
I enter the displayed code into the google account. I get the confirmation message that the device was linked. I also receive the email that a new device was granted the access to the calendar.
So far so good, unfortunately, in HA I get the message the code expired
This is as far I have come with the installation.