Hi @femilshajin,
Thanks for the reply.
To add users to your organization, you could configure it to Enable Auto-Membership, as described in Grant Just-In-Time Membership to an Organization Connection.
(Reference: Configure Inbound SCIM)
Alternatively, you could directly Assign Members to an Organization.
Then, you can follow our Assign Members to an Organization documentation to assign them to roles via the Management API after they have been onboarded.
Let me know if you have any additional questions.
Thanks,
Rueben