Running Foolcat in a VM is a Pro feature.
If you see this error when activating a trial, you're running Foolcat in a VM, or a Hypervisor process must be active in Windows.
If you see this error when activating a purchased license, you have a regular license or a Pro license that needs VM activations allowed on your license.
A step-by-step guide for disabling any-and-all Hypervisor (Hyper-V) and Virtual Machine features on your PC is available here:
You're likely on an old version of Foolcat, update to the latest version.
Foolcat's media engine isn't starting properly. Reboot your computer, and if that doesn't help, reinstall Foolcat.