On top of that tip from @stephenw10 you should be able to set up also the following things;
Create a user for each device and user that should be connect to the NAS
According to that users set up user Privilegs to the files and folders on that NAS
Set up on the PCs shortcuts to that NAS folders.
If you are using LDAP and/or Radius don´t forget to sort
all users/PCs with an certificate and/or set up the machines
correctly in the LDAP role
Either working with VLANs and/or plain routing you must
set up firewall ruiles on the pfSense according to both
subnets or on the Switch you are using the right
matching ACLs.