First, you will in most cases be better off using reverb as a send rather than an insert on an audio channel.
since it’s hardware we are talking about, you will need to configure an “external effect” (see VST connections in the Device menu) to allow Cubase to send the signal through specified hardware outputs and receive the inputs from the reverb - plural because it’s likely a stereo effect.
Once you’ve configured the external effect it will appear in your plug in list. (Assuming you’ve actually patched the reverb to to specified I/Os, all you have to do is select it and insert it on the channel - again, using an effect channel is recommended so you can send signals from more than one audio channel to it.)
There is a latency calculator you can click on to correct for the round trip time, but reverb confuses it. to get that right you have to send it to and from the reverb with the wet/dry mix on the hardware set to totally dry.