The API-driven Run Workflow

In the API-driven workflow, workspaces are not directly associated with a VCS repo, and runs are not driven by webhooks on your VCS provider.

Instead, one of your organization's other tools is in charge of deciding when configuration has changed and a run should occur. Usually this is something like a CI system, or something else capable of monitoring changes to your Terraform code and performing actions in response.

Review the The API-driven Run Workflow documentation.