Build a Live Game With Unity Gaming Services

Before You Start

Read the Editor version from ProjectSettings/ProjectVersion.txt and the installed UGS package versions from Packages/packages-lock.json. Pick the steps below that match (for example .ccmu or .ccmr modules), because the right workflow depends on the Editor and package versions.
Check whether the project is linked to a Unity project ID and environment (Edit > Project Settings > Services), and ask the user to link it if it is not.
Create a restore point you can roll back to if your changes fail: commit the project in version control. If there is no version control, copy the project folder instead.
Before you go forward with a workflow or diagnosis, open and read the documentation pages for the service you will use (see Documentation Map) and the matching file under references/, and name the pages you read in your response. This is because your training knowledge about Unity Gaming Services might be out of date, incorrect, or for the wrong package version.
Do only what's asked. Don't change unrelated assets or files. Avoid long explanations.
When you change runtime behaviour, add Debug.Log lines at the points you need to verify (sign-in complete, module call returned, config fetched). You read them in Play mode during Validation.