Migration of 6TB to Box

I am attempting to migrate 6TB to box from a Network attached Storage that is mapped to network Drive on my Windows PC. What is the best method to accomplish this. I currently have installed Box Drive and I migrated a few GBs using windows explorer and teracopy but I'm not sure if this is the best option. I considered using the ftp service but I am not able to enable it from the admin console of box. Any direction or support is much appreciated.