Remote Application Helper (RAH): Installation through Group Policy (GPO) or by using a script

Resolution

First, you need to have a setup of the Remote Application Helper. 
Mind that new Parallels Secure Workspace versions may bring improved versions of the Remote Application Helper (sometimes even just the "patch level" is updated, but the version number stays the same). It's important to keep this up to date. 
The helper is backward compatible.

The setup can be downloaded by anyone who has access to an application with the smartcard: label.

1. Log in to the Workspace.
2. Click the username (bottom left) and go to Account Settings.
3. At the bottom of this list, there should be a Download Remote Application Helper link.

Important: the installation must be run with elevated user rights. So when using a Group Policy (GPO) to deploy this, link the setup script to the "Computer configuration" (and not the User Configuration). This is because the installer needs to write a few entries to the Windows Registry to create a new URL handler.

From version 5.3 onwards:

Create an installation script. A PowerShell example:$argumentList = @(
 "/i 'C:\setups\Remote Application Helper.msi'", # Adjust path
 "/quiet"
)
Start-Process msiexec.exe -ArgumentList $argumentList

All the typical msiexec parameters can be used.

Before Awingu 5.3:

Create an installation script. A PowerShell example:

Start-Process C:\setups\RemoteApplicationHelper_windows_4_1_0.exe -ArgumentList "-q -overwrite"

Overview of the parameters for the setup executable: