I would start with the midi section of the op-z manual - https://teenage.engineering/guides/op-z/midi
Also the op-z midi thread is a good place to see what other people have done, what issues they have had and how they have solved or worked around them - Op-z MIDI Thread
I don’t know if the circuit sends midi or how that is configured, but if it can send midi messages the op-z can receive them.
I use a launchpad pro mk3 for this. I bought
the recommended usb hub from Kingston, the nucleum.
Plug into the usb on the opz and then plug the launchpad into usb and works straight away. I then use the scale and chord modes to input notes to the opz