How to get Account ID of SCIM provisioned user from external IdP so they can login?

I have added an external Identity Provider, and configured SCIM for automatic provisioning. I now have a user in IAM Identity Center from this IdP. How can I find the Account ID of this user so they can log in (or how can I have it emailed to them or whatever)?

I have tried very hard to search the official documentation but simply cannot find the solution to this.