The full error message is: "Internal error: An attempt was made to access WizardForm before it has been created."
This occurs in some situations when you don't have .NET Framework 4.8 installed. The EpicTable installer is supposed to detect that and install it for you, but that's not what's happening. I'll have to check that out. Meanwhile, you should be able to install if you first install the .NET Framework 4.8 Runtime.
Let me know if this doesn't solve the problem.