Error accessing Power BI REST API: Admin - Get Activity Events using Service Principal auth

Hello,

I try to access the Get Activity Events using Service Principal auth with Python.

I did succesfully manage to obtain the token, however using below's code I get the following error upon retrieving activity events from the API..

{'error': {'code': 'PowerBINotAuthorizedException', 'pbi.error': {'code': 'PowerBINotAuthorizedException', 'parameters': {}, 'details': [], 'exceptionCulprit': 1}}}

import adal
import requests
import json
import datetime

tenant_id = ""
authority_url = 'https://login.microsoftonline.com/'+tenant_id+'/'
resource_url = 'https://analysis.windows.net/powerbi/api'
client_secret = ""
client_id = ""
context = adal.AuthenticationContext(authority=authority_url,
                                     validate_authority=True,
                                     api_version=None)
token = context.acquire_token_with_client_credentials(resource_url, client_id, client_secret)
access_token = token.get('accessToken')

print(requests.get(f"https://api.powerbi.com/v1.0/myorg/admin/activityevents?startDateTime='2021-07-22T00:00:00Z'&endDateTime='2021-07-22T23:59:59Z'", headers = {'Authorization': f'Bearer {access_token}'}).json())

- I enabled Service Principal Read Only API in the admin portal in Power BI.

- I added the App Registration to the security group that is assigned in the setting

What am I doing wrong?