The zenOn setup also includes a setup for the WibuKey software. This setup throws an error message on 64 Bit Windows systems.
The reason for this error message is that the WibuKey setup has problems to handle the path names which are longer then the ones on 32 Bit machines. A solution would be to execute the 64 Bit WibuKey setup separately (the setup file is settled on the zenOn setup CD in the section "Additional software").