After a release train has been published and is in the Approved state, it can be executed.
In the default workflow, the release train can still be returned to the Planning state from the Approved state if you need to change the associations. After you click Execute, the release train’s application releases’ release packages are deployed and installed according to the deployment task definitions that you have previously configured.
To execute a release train:
Navigate to a release train that is in the Approved state.
Click Execute.
The release package enters the In Progress state. The release train remains in the In Progress state until it progresses to one of the completion states, Close or Release Fail.