Hello @Ricardo H,
Thank you for posting your query on Microsoft Q&A.
I understand that you have an External ID tenant with Microsoft Entra ID Free license and when you are trying to access User Settings page with Global administrator credentials, you are getting the error as "This feature is unavailable or doesn't apply to the current tenant configuration".
Please note that this User Settings Configuration page is currently not accessible and not supported feature in External tenants.
To confirm this, I have tested in my test environment by creating one External tenant by signing in to the Microsoft Entra admin center.
After creating an External tenant, when I tried to navigate to Identity ->Users -> User Settings page, I got the same error as mentioned in the below Screenshot for your reference.
Please refer to the below document to know about the Supported Features available in External tenants.
External Tenant Features - Microsoft Entra External ID | Microsoft Learn
Please note that the document which you have shared where the User settings configuration page is accessible is completely related to the normal Microsoft Entra Workforce tenant.
Manage the 'Stay signed in' prompt in Microsoft Entra ID - Microsoft Entra | Microsoft Learn
I hope this above information provided is helpful. Please feel free to reach out if you have any further questions.
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