Hi @viacheslav.k,
Welcome to the Community
When you try to export user at Auth0 system using bulk import API there is some limitation on it. Every single hit at https://.auth0.com/api/v2/jobs/users-exports API will be consider a job. So by default you can only run 10 job simultaneous and wait them to complete until you run another job. You can ask auth0 support team if you want to speedup the export job process.
Hope answered the query, please let me know if need to explain anything else.