boot USB for Windows install error

[MaxUser]

Created a new Windows 10 VM.
I have a USB drive that is bootable for installing Windows.
First, is this the correct method of setting up a VM and to install Windows via the USB drive? I've installed Windows in a non VM from the bootable USB so I'm thinking it should work for a VM.
The usb drive is set up as

• SATA Port 0: usb.vmdk
  SATA Port 2: 50GB HD
  8192MB for Base memory

I'm getting this error when the VM starts up and I select the USB as the boot device and not sure how to fix:

An error has occurred during virtual machine execution! The error details are shown below. You may try to correct the error and resume the virtual machine execution.

The I/O cache encountered an error while updating data in medium "ahci-0-0" (rc=VERR_ACCESS_DENIED). Make sure there is enough free space on the disk and that the disk is working properly. Operation can be resumed afterwards.

Error ID: BLKCACHE_IOERR
Severity: Non-Fatal Error

[mpack]

Your can't install an OS from USB in VirtualBox. Get yourself an ISO and see chapter 1 of the user manual.

[MaxUser]

Thank you.