Oops, nevermind, I jumped the gun.
I called tech support and they were very helpful.
It turns out that the dongle didn't match the serial number of the software so they issued a new serial number to me.
I had a couple of other problems and they gave me some suggestions and all is well.
Bob
I purchased Vectorworks 10 Educational version only to discover it uses a USB "Dongle".
Sigh...
I bought a USB card to add USB functionality to my older Mac G3, plugged in the dongle which lights up a red led but the software won't run!
I see that there are other posts with the same issue. I have sent an email to Nemetschek and await enlightenment.
Is a replacement the only solution?