The following considerations should be reviewed before implementing Flow for customer onboarding:
Use Field Level Security on Milestones, which is a setting that controls whether users can view and edit fields on records. The Admin should use Field Level Security to restrict access to the Milestones field on the Flow Template object, which is used to track the progress of customer onboarding flows2.
Flow for Financial Service Cloud is not available for the Individual Object Model, which is an alternative data model that uses the Individual object instead of Person Accounts to store information about people. Flow for Financial Service Cloud only supports Person Accounts as the primary object for customer onboarding flows2. Verified Reference: 2