Tableau license says its a named user license which means only one user can activate/register the product. Better raise your way of usage with Tableau to get clear usage instructions to your situation.
Tableau was not designed or officially supported using RDP into a Windows Server. We do support having remote desktop support using VMWare or Citrix where each user gets their own virtual PC.
Running Tableau on Windows Server for multiple users would violate the EULA. Only one user can access Tableau Desktop on each PC or Mac. Besides, performance would be dismal if you could run multiple users on Windows Server. Tableau is a client/server solution where users are expected and licensed to one user login per PC or Mac and Tableau Server running centrally.
If you want virtual desktops, then you would need to purchase VMWare or Citrix where virtual desktops are supported because they isolate each user to their own OS instance remotely. There is a performance hit when using remote desktops, from my experience.