Does the 3.5 AWS Partner CRM Connector still use S3 buckets?

No, the CRM connector now uses an API instead of S3.

In November 2024, AWS released an updated version of the CRM connector for ACE partners that uses the Partner Central API.

The 3.x version now supports the Partner Central API as the preferred integration for ACE instead of the older S3 CRM integration.

The 3.x connector is backwards compatible with S3, but partners just getting started must use the Partner Central API.

Important note about Leads: At this time partners who receive ACE Leads from AWS will implement this with S3.

AppExchange install page for AWS Partner CRM Connector:
https://appexchange.salesforce.com/appxListingDetail?listingId=a0N4V00000IYf0nUAD

AWS docs for CRM integration:
https://docs.aws.amazon.com/partner-central/latest/crm/aws-partner-crm-integration.html

AWS docs for Partner Central API:
https://docs.aws.amazon.com/partner-central/latest/APIReference/aws-partner-central-api-reference-guide.html