If you have had Orca3D installed on your home computer in the past (for example, an evaluation license), you will need to follow these steps for a new installation. Step #2 is important; otherwise you will not be given the opportunity to enter a License Key.
a. Using Control Panel, uninstall Orca3D
b. Delete the folder:c:\ProgramData\BCO\Orca3DV1 for Version 1, or c:\ProgramData\BCO\Orca3DV2 for Version 2
c. Install Orca3D. The installation files are here:
Orca3D Version 2 for Rhino 6
Orca3D Version 1 for Rhino 5
d. Start Rhino; you will be given the opportunity to enter a new License Key. Remember that sometimes the Orca3D license dialog is “hidden” behind the Rhino splash screen; if Rhino seems to be “stuck,” please look for the Orca3D license window behind it (you can use Alt-Tab to cycle through the open windows on your computer).