Thank you very much for the response.
I tried the remote location with a colon :, too.
This gives the following errors:
>rclone -vv mount nextcloud: n:
2021/06/03 17:19:41 DEBUG : Using config file from "C:\\***\\rclone\\rclone.conf"
2021/06/03 17:19:41 DEBUG : rclone: Version "v1.55.1" starting with parameters ["rclone" "-vv" "mount" "nextcloud:" "n:"]
2021/06/03 17:19:41 DEBUG : Creating backend with remote "nextcloud:"
2021/06/03 17:19:41 Failed to create file system for "nextcloud:": didn't find section in config file
Same config as before, of course.