Using Citrix XenApp USB Forwarding

Requirements

Start Citrix Studio
Go to "Policies" on the left-hand side.
Either edit an existing policy, or create a new policy.
Edit "Client USB device redirection", set it to "Allowed".
Edit "Client USB device redirection rules", click "New" and type: "Allow: VID=18FB" (space and capitalization is important, no quotes).
Click "Finish" and close Citrix Studio.

Open the group policy editor for the policy controlling your Citrix Receiver client's.
Go to Administrative Templates -> Citrix Components -> Citrix Receiver -> Remoting client devices -> Generic USB Remoting (if this is missing you need the Citrix Group Policy Extensions, see here).
Open "New USB Devices", select "Enabled", click "OK".
Open "Existing USB Devices", select "Enabled", click "OK".
If you need to restrict which devices get automatically forwarded, open "USB Device Rules", add the required rules and hit "OK".
Run "gpupdate /force" as an administrator on the client computer you're testing on to make sure you have the newest version of the policy.

Create a new key located at: HKLM\SOFTWARE\Citrix\ICA Client\GenericUSB\Devices\VID18FB PID0200 (replace PID0200 with the product id for the product you're looking to forward).
Create a new DWORD value named "AutoRedirect" and set it to "1".

Citrix Receiver installs two drivers to support USB forwarding functionality
In a command prompt run: driverquery
A list of installed drivers should display
Verify that both ctxusbm and Ctxusbr are in the list
If a driver is missing, attempt a reinstall of Citrix or contact support to attempt to resolve the missing driver issue