Question Don't know use Access Tokens , private bucket

I have created a private bucket,
For test, I get the Bucket Access Tokens: d107a7014d8de3b5d410ef902607b335,

After reading the documentation, I realized that I need to authenticate the token in the form "usernameassword" and the username needs to be empty.

So I use ":5675c7320b732302c5e08ed0e81c508a"
Then got base64-encoded: "OjU2NzVjNzMyMGI3MzIzMDJjNWUwOGVkMGU4MWM1MDhh"

Finally I executed the following code:

Code (CSharp):

1.             Addressables.WebRequestOverride = webRequest =>
2.             {
3.                 webRequest.SetRequestHeader("Authorization", "OjU2NzVjNzMyMGI3MzIzMDJjNWUwOGVkMGU4MWM1MDhh");
4.                 Debug.Log($"Fetching: {webRequest.url}");
5.             };
6.             handle = Addressables.LoadAssetAsync<AudioClip>(auName);

Got the error
RemoteProviderException : Unable to load asset bundle from : https://7f946db4-cb70-4bb2-9159-8c7...s_all_3765caabd9a123364042eef62f516ce8.bundle
UnityWebRequest result : ProtocolError : HTTP/1.1 401 Unauthorized