Windows Virtual Desktop and PDF Creator Terminal Server


I'm currently migrating a customer from RDS/Terminal servers to the new Azure Service - Windows Virtual Desktop.
This service works with the new Windows 10 multi-session OS that allow multiple users to share a Windows 10 virtual machine.
I'm preparing the image (installling the apps) and I cant use the classic PDF Creator installer because it seems it detects the RDS service on Windows 10 multi-session.

Before, the customer had 3 servers for 100 users, that means 3 servers licences. Now the customer will have 20 Windows 10 multi sessions. Does he have to buy a licence for each virtual machine (a licence for 5 users for example) or is there another solution less expensive ?

Thank you in advance for your help.