Hey Dusty,
FreeNAS is using plugins for some advanced and non-file related services like Plex Server or Nextcloud. These services go beyond file sharing. Samba is standard, basic file sharing. As such, you do it straight from FreeNAS itself. You setup your storage, accounts and permission before setting the file sharing protocol itself. NFS, Samba, AFP, FreeNAS do them all straight from its WebUI.