Single user access to specific folder in group folder

I created users, grouped them, created group folders and sub-folders. All works fine. I have one user that is supposed to see only one sub-folder in one group. I saw the possibility to share with his email address. Is there another way through settings to just set the allowed sub-folder?

You can not only share with email but also with real user in your next cloud, guest user in your nextcloud and ferderated sharing with user from another nextcloud.

Thank you for your kind response. I was probably not clear. I am aware of the mentioned possibilities of sharing. I do not need these with users of the same group. The question was rather how do I grant one user access to a specific sub-folder without using the fork?

For example: I have a group folder Projects. This folder has one subfolder for each client. While my staff has access to all subfolders via group membership, it seems that I cannot create a “group” for a subfolder. Like I said, I am aware of being able to use the fork in order to share. I just prefer to manage all users in one place.

Perhaps you can read.

https://nextcloud.com/blog/nextcloud-16-implements-access-control-lists-to-replace-classic-file-servers/

https://apps.nextcloud.com/apps/files_accesscontrol

I do not know if it possible to use other groups in group shares. Perhaps you must use different group folders.