Setup workflows are apart of the CircleCI dynamic configuration feature. This allows for conditional and dynamic generation of configurations depending on pipeline values or file paths.
This error will be encountered if you attempt to re-run the setup workflow from the UI.
For security and consistency reasons, continuation is allowed once per pipeline, and only for a certain amount of time after the setup phase started. This is due to a one-time-use token that is used by the setup workflow to create more workflows via a pipeline continuation API. To solve this issue, make a fresh commit and PR to trigger a new pipeline which will result in the creation of a new token for the setup workflow.