Each out-of-the-box Change Management System requires configurations to work within your installation. These guides will assist you in finding the values you need and setting up a successful Change Management System Integration.
At high level, you will
Configure change management instance on Integrations page.
Additional configuration to update comment and/or status can also be done.
Configure your folder(s) or pipeline for using one or more such change management instance (note that configuration are inherited in folder hierarchy and can be overridden as desired.
Submit a deployment or create a snapshot to put the approval via CMS in action. The deployment will stay in an approval status until the external CMS completes that task (approve or reject).
Enable out of the box change management system integrations based on following guides.