UnauthorizedAccessException while Create governanceRoleAssignmentRequest via Microsoft Graph api

Question

My requirement is to Assign the 'User Access administrator' role Azure AD security Group using the microsoft graph api.

https://learn.microsoft.com/en-us/graph/api/governanceroleassignmentrequest-post?view=graph-rest-beta&tabs=http

My registered app in azure AD have the below API permission,

Directory.Read.All
PrivilegedAccess.ReadWrite.AzureAD
PrivilegedAccess.ReadWrite.AzureResources

Below is the request body
{
"roleDefinitionId": "18d7d88d-d35e-4fb5-a5c3-7773c20a72d9",
"resourceId": "<subscription Id>",
"subjectId": "<Azure AD group Object Id>",
"assignmentState": "Eligible",
"type": "AdminAdd",
"reason": "Assign an eligible role",
"schedule": {
"startDateTime": "2021-12-08T23:37:43.356Z",
"endDateTime": "2021-12-10T23:37:43.356Z",
"type": "Once"
}
}

while executing getting the below response

{
"error": {
"code": "UnauthorizedAccessException",
"message": "Attempted to perform an unauthorized operation.",
"innerError": {
"date": "2021-12-09T07:52:42",
"request-id": "c111b180-322a-41f9-b072-29385b4b2199",
"client-request-id": "c111b180-322a-41f9-b072-29385b4b2199"
}
}
}