It doesn't have to be root. A domain user in the administrators group also should work. The API calls (cifs-share-list-iter-start, cifs-share-list-iter-next, cifs-share-list-iter-end) listed in the netapp thread below is exactly what Storage Manager uses as well
vfiler tunneling in combination with non-root user | NetApp Community
is your domain account an administrative user on the netapp filer? If not, you will need to ensure the user role should cover the ability to invoke these api calls. The netapp thread above also has the syntax to add these permissions to the user role. any vfilers involved here?