You can use Nextcloud exactly as you want to.
I run Nextcloud (on Linux) with a Windows file server (in domain). You can connect with smbclient (part of Nextcloud) Windows Shares (or others) and map them into the file hierarchy of Nextcloud.
E.g. You have a Windows share \\WinSrv\Books and can map it as Books (or what ever name you like) into Nextcloud. On Windows side it behaves like a normal share. On Nextcloud it behaves similar to a Nextcloud directory. Not sure if it still has some limitation compared to an in-nextcloud-directory.
Yo can configure that in Administraton settings - External Storage for all users or by user (SMB/CIFS).
The configuration above is a global one (but âonlyâ an example. I use DFS). I used Login and password for authentication because when I setup my NC there was nothing else which worked. Now there are other options.
It will than look like this:
While Backups is a normal Nextcloud directory.
This feature was one of the reasons I use Nextcloud.