You are syncing records from your CRM to Outreach and you see this error: The requested resource does not exist
Check the owner of the record in your CRM. Make sure that user exists in Outreach and is mapped in the Outreach plugin on the User object. Please see our How To Map Users in the CRM Plugin article if you need a refresher on that.
If it is a placeholder/blanket user that you use in your CRM, then you can also simply change the owner to an active user that also exists in Outreach.
This error appears when the systems are trying to sync with each other, but it cannot find that user/owner record.