CTI - Zammad endpoint configuration

I am trying to integrate Zammad into our VitalPBX.
It is for a “generic CTI”, just to have a call logs available on the Zammad portal.
The instuctions from Zammad says:
Configure Zammad Endpoints in PBX and it gives you the URL https://FQDN/api/v1/cti/secretkey.

Where or how do I input this URL in my VitalPBX installation?

I am gratefull for any hint.