We're not able to provide access to database files or volumes while a workspace has no active plan, so there's no way to download or transfer them in this state.

To get access back, pick a plan for the workspace: either Downgrade to Free on the Plans page (non-cron services run with App Sleeping on Free), or subscribe to Hobby from Billing. Then redeploy the database service and export the data yourself, for example with pg_dump or your database's equivalent.