Permission denied when trying to Initialize google earth engine

I was following the google earth engine documentation here. I added all the files in the root of my project as per the documentation. These files are the config.py and the privatekey.json. I then wrote the following code:

import ee
service_account = '<service-acc>@<project-id>.iam.gserviceaccount.com'
credentials = ee.ServiceAccountCredentials(service_account, 'privatekey.json')
ee.Initialize(credentials)

When I run this code, I got this error:

Traceback (most recent call last):
  File "/home/thuha/miniconda3/envs/prj/lib/python3.8/site-packages/ee/data.py", line 345, in _execute_cloud_call
    return call.execute(num_retries=num_retries)
  File "/home/thuha/miniconda3/envs/prj/lib/python3.8/site-packages/googleapiclient/_helpers.py", line 134, in positional_wrapper
    return wrapped(*args, **kwargs)
  File "/home/thuha/miniconda3/envs/prj/lib/python3.8/site-packages/googleapiclient/http.py", line 907, in execute
    raise HttpError(resp, content, uri=self.uri)
googleapiclient.errors.HttpError: <HttpError 403 when requesting https://earthengine.googleapis.com/v1alpha/projects/earthengine-legacy/algorithms?prettyPrint=false&alt=json returned "Permission denied.">

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "<console>", line 1, in <module>
  File "/home/thuha/miniconda3/envs/prj/lib/python3.8/site-packages/ee/__init__.py", line 125, in Initialize
    ApiFunction.initialize()
  File "/home/thuha/miniconda3/envs/prj/lib/python3.8/site-packages/ee/apifunction.py", line 154, in initialize
    signatures = data.getAlgorithms()
  File "/home/thuha/miniconda3/envs/prj/lib/python3.8/site-packages/ee/data.py", line 1052, in getAlgorithms
    return _cloud_api_utils.convert_algorithms(_execute_cloud_call(call))
  File "/home/thuha/miniconda3/envs/prj/lib/python3.8/site-packages/ee/data.py", line 347, in _execute_cloud_call
    raise _translate_cloud_exception(e)
ee.ee_exception.EEException: Permission denied.

I need to know what makes that error appear when I want to initialize.

Google documentation