BKOOL recently updated their simulator, which also changed how you update your trainer to FE-C. We recommend contacting BKOOL through their support site for more assistance.
Once you've updated your trainer, the pairing process is the same as other smart trainers.
Fire up Zwift and begin the pairing process by choosing Smart Trainers.
After you've selected it, your pairing screen will look like this:
You'll notice that Cadence is also paired. You can unpair this as the Bkool trainer only gives virtual cadence, which Zwift does not use.