Permissions to a folder only

I've got a local Windows account. I'm trying to allow the user to log into the vSphere client, but only see VMs in a particular folder (the "dev" folder).

As it stands, the user has been assigned the "Virtual machine administrator" role on the datacenter. When I log into the vSphere client, I can see all of the VMs in the cluster. I granted permission on the folder, to the "Virtual machine administrator" role, but when I log in and select VMs and Templates, nothing is visible.

How can I set this up so the user has VM admin rights, but only to the VMs in the dev folder?

Thanks.