Before installing the interface ensure that all Jarrison Time components installed on the computer are closed or stopped.
Then install the interface found in the Downloads section of the website.
Finally, the .dll files need to be properly registered with Windows. This is done through two batch files, named RegisterZKBioKey.bat and RegisterZKDLL.bat. Select each one and then right-click and Run as Administrator.
It may happen that the services do not register correctly. In this case, uninstall the ZK interface through Control Panel > Programs and Features, and repeat the above steps.