Why am I getting "This desktop currently has no desktop sources available" when connecting to VirtualLab@APU?

When connecting to the Windows 10 virtual machine using VMware Horizon Client or HTML Access, you encounter the following error:

The reason of this error is that VirtualLab@APU have reached its maximum number of users allowed to connect to the service. Currently, the Virtual Lab service can accommodate up to 50 simultaneous users' active sessions.

As a gentle reminder, please shutdown the virtual machine once you no longer need it to free up the resource for other users.