Keeping the folder structure safe from user editing / deletions and giving the users freedom for the content

I am setting up a nextcloud instance where i need the following:

All users belonging to a specific group to be able to add/edit/remove files , BUT i need them to NOT be able alter the folder structure.

For example i have a strcture like:

Folder 1 → Folder 1-2 → Subfolder 1-3
Folder 2 → Folder 2-1 → Subfolder 2-3

I need the users to be able upload, delete, download files in sub folders but not being able to delete the parent folder structure.

The files are in external storage (local).

I tried sharing Folder 1 and Folder 2 and adjusting the permissions but when i add it to the user, he is able to delete the parent folder from the Actions menu.

Is there any way to do this?

P.s. I found a similar post that has the same requirement, but in the end there is no explanation how to edit individual folders and set permissions based on groups. Where can i find this info?