Troubleshooting DBMS_CLOUD access to object storage

Summary:

I tried to access the object storage from ADB (free tier) but failed with "ORA-20401: Authorization failed for URI".

1. Is access to object storage supported in free tier?
2. How do I verify the auth token? (i.e., Can I use the auth token to access the object storage without using the DB?)

Content (please ensure you mask any confidential information):

1. I created a bucket and set visibility to public and uploaded some files there
2. I generated an auth token in cloud console
3. I created a credential in my free tier DB

BEGIN
  DBMS_CLOUD.CREATE_CREDENTIAL(
    credential_name => 'MY_CREDENTIAL',
    username => '(my OCI login username)',
    password => '(my auth token)'
  );
END;
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