Having trouble setting up and instanciating a service account

I have set up an application. 
I have specified the authentication method as OAuth 2.0 with JSON Web Tokens (Server Authentication) 
I have specified the app access level to App + Enterprise Access
I have valid oauth2 credentials. 
I have the following application scopes enabled.

• 1- Read all files and folders store in Box Access to content is further restricted by the user' permission and Access Token used
• 2- Write all files and folders store in Box Necessary to download files and folders.  Access to content is further restricted by the users' permission and Access Token used.  Read access is required when Write access is selected. 
• 4- Manage Users
• 5- Manage Groups
• 6- Manage retention policies for use with the governance add-on7- Manage enterprise properties for use with the event stream, enterprise's attributes, and device pins.  App + Enterprise Access is required to use this scope. 
• Manage enterprise properties for use with the event stream, enterprise's attributes, and device pins.  App + Enterprise Access is required to use this scope.
•  

I have set Advanced Features of Generate user access tokens
I have added a public key
I have downloaded and correctly setup a config.json.  
I am using the JWT auth code that was specified in the documentation. 
 

    auth = JWTAuth.from_settings_file('config.json')
    client = Client(auth)
    service_account = client.user(user_id='me').get()
    return service_account

I am still getting the following error: 

 

auth = JWTAuth.from_settings_file('config.json')client = Client(auth)service_account = client.user(user_id='me').get()print(f'Service Account user ID is {service_account.id}')return service_account

Also, I invited the service account to collaborate on my files.  

Please help me sort out this error. 

Thanks in advance

Lois

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