The program didn’t accept the license key for Mac on Rhino 5 because it was a key for Windows version (in the email). While I accurately downloaded Rhino 5 for Mac. How to find the correct key?
It sounds like you tried to use a V6 key in V5 for Mac.
That won’t work.
That’s the only way I know to get that message.
Doesn’t the message with the Rhino license key describe it as a “V6” license?
The key will also start with “RH60-xxxx…” indicating Rhino V6.