Backing up to external USB 3 Hard disk - to have an offline copy of the data.

Hi
 
We have Dell SAN and 2xPowerEdge Servers and they are connected to each other using 12Gbps SAS cable.
 
The PowerEdge servers have a 10Gb LAN card are connected to the HP 10 gigabit Core switch.
 
Now I am planning to do an offline backup, I have 2.5Tb of data on a Windows 2012 Virtual file server and would like to backup to the external hard disk.
 
I am planning to buy a new server with a 10GB LAN card in it and install windows 2019 OS - then connect this server to the core switch.
 
From this Windows 2019 server, I would like to connect the USB3 Hard disk to the server USB 3 Port and use ROBOCOPY to copy 2.5 TB of data to the external Hard disk.
 
I would like to do this starting from Monday evening and by the time I come to the office the next day morning, I would like the backup completed and I can remove the external HDD and keep it in the safe.
On Tue I can put another external disk and do the same and do this till Friday and follow same sequence.
 
Please can you advise if this setup will work and will the backup complete before the start of the next day?
 
Any help and suggestions much appreciated.
 
Thanks