Step-1: Create a User & User Group
Steps to Create a User
Login to your OCI console where parent billing account exist.
Navigate to Profile > Identity domain: Default.
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Go to Users < Create User
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Enter First name, Last name & email address.
Click on Create button.
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Create a User Group & Assign user
Go to Groups > Create Group
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Enter Group name.
Choose the user created in step-1 and assign to the group.
Click on Create button.
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Please capture the group name as you will need them for subsequent steps.