Users with Business Premium License can see the content of labeled encrypted files?

Great questions! Thanks for reaching out Pedro!

1. Sensitivity labels can be applied to files stored in Microsoft Environment. However, applying sensitivity labels directly to files stored in AWS Shared Drives and AWS S3 buckets is not natively supported by Purview Information as these are different environments where we may not have direct access to apply the protection features.
2. Yes, sensitivity labels can be configured to both classify and encrypt files. When a sensitivity label with encryption is applied to a file, only users who have been granted access through the label's permissions can decrypt and view the content. 
   The documentation (Apply encryption using sensitivity labels | Microsoft Learn) states that “When a document, email, or meeting invite is encrypted, access to the content is restricted, so that it-Can be decrypted only by users authorized by the label's encryption settings.”
   Helpful documentation here- https://learn.microsoft.com/en-us/purview/sensitivity-labels?view=o365-worldwide#what-sensitivity-labels-can-do
3. For encrypted files, the ability to decrypt and view the content depends on the permissions set in the sensitivity label. If a Business Premium user is included in the permissions, they will be able to decrypt and access the content. This document provides a detailed description of what to expect based on the licensing. Microsoft Purview service description - Service Descriptions | Microsoft Learn