OK. So you have a license on the dongle for Cubase Artist 6. Your picture 2.png is irrelevant. Of course, it won’t let you download ANOTHER license on the same activation code but you don’t need to anyway. The license is already on the dongle.
Now we just need to confirm that you are, in fact, trying to start Cubase Artist 6. I am not sure how you can show that. A picture of the icon or the installed program version from “installed programs” or whatever the Mac equivalent is.
The other thing is that I notice you have an educational license. I really have no idea if there are any other restrictions on those licenses such as one computer only, etc., so I can’t really help there.