Sharing a Nextcloud Calendar in another Nextcloud Calendar

Hi,
I would like to integrate a calendar (A) from another Nextcloud instance in my Nextcloud calendar (B). Sharing the calendar (A) e.g. in Thunderbird works fine - I enter the iCal link, user and password and it works.
But when I add a remote Calendar (A) in my Nextcloud Calendar (B), I can only enter the iCal link, and get the error message that the other server denies the access - seems to be right, because it probably tries with the credentials of the Nextcloud instance (A). Where can I enter the credentials of the remote Calendar?
I am using Nextcloud 17, and Calendar 1.7.1

same on my site. Do you have python available?
If yes, please send me the output of:

#!/usr/bin/python3
from webdav3.client import Client
options = {
‘webdav_hostname’: “https://nextcloud.heissa.de/remote.php/dav/calendars/gh2/”,
‘webdav_login’: “user”,
‘webdav_password’: “passwd”
}
cal0 = “personal”
cal1 = “wwwfewo-direktde”
remotecalendar = “your_remote_calendar”
client = Client(options)
res = client.info(cal1)
print(res)
files = client.list(remotecalendar)
print(files)
client.pull(remote_directory=cal0, local_directory=’/tmp/’)

As far as I know this has not yet been implemented. See here for more details:

The best way to do it is to create a public link for calendar A and subscribe to it on instance B.