Hi,
403 Error seems like a RBAC role issue, do you have full access or delegated access to the Azure Tenant to make changes? Check with the tenant admin to provide access so you can make changes to this policy.
Also with regards to Password policy check if you have combined registration option enabled on the tenant - https://learn.microsoft.com/en-gb/azure/active-directory/authentication/concept-registration-mfa-sspr-combined
Hope this helps.
JS
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