Security style just covers how you want to handle permissions.
If you want UNIX perms, use UNIX security style. NFS users will use a UID/GID to gain access based on how you set the volume permissions.
If you want Windows perms, use NTFS. Then the user will need to map to a valid Windows user.
This blog also covers it.
https://whyistheinternetbroken.wordpress.com/2019/02/05/windows-nfs-who-does-that/