Approval process for external user creation

Hello!
We would like to create an approval process every time an external user is created from the web portal by an employee (we don't want an attestation process, but an approval process); the approver should be always the manager of the creator. We thought about creating a process in the "process orchestration" section in the Designer.
The example we were inspired by is the process that at the moment of the user's self-registration, requires the user's attestation (“VI_Attestation_Org_new_AttestationCase_for_Certification”).
We have seen that in the field "ObjectType" is inserted the value "AttestationPolicy " and in the field “MethodName” is inserted the value "CreateAttestation" and the process is connected to the table “Org”.
Now we have two questions:
1) To which table should we link our process in order to run it before the user is created?
2) What values should be used for the "ObjectType" and " MethodName" fields to create an approval policy and not an attestation policy?
Any other suggestions is very appreciated.

Version: 8.1.4 (onDemand solution)

Thanks,
Martina