I think you need to find out what the client is really trying to achieve and why there are multiple servers etc.
You could do two ways:
simplest way is to present the NetApp storage as a NAS volume using CIFS or NFS. The application / process(es) on the server(s) that needs to write the data will need to be running as a user with access to the filer. ie if using CIFS an AD user, or server could simply be left logged in as a user with these rights.
The other way could be try it the SAN way, run MS clustering software in Active / Active and present the storage as a LUN to both servers.
I guess the third way could be to use VFM or similar replication software.
All this is assuming both servers never try to access or modify the same file at the same time.
I think you've a bit of trail and error ahead of you!
Good luck