Hi,
It will not be possible to load so many users on a single Windows Server, I will recommend you to follow and read the server sizing articles, also the applications, user profiles and GPU should be consider when you are planning to deploy RDP server.
Choose your licensing based on what makes sense for your company. License per user to enable users to remote on any of their devices in a BYOD scenario. License per device if users share the same devices. Per User Client Access Licenses is best option and you can check out more details on this over here - rds-client-access-license
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