A company has an on-premises application that uses SFTP to collect financial data from multiple vendors. The company is migrating to the AWS Cloud. The company has created an application that uses Amazon S3 APIs to upload files from vendors. Some vendors run their systems on legacy applications that do not support S3 APIs. The vendors want to continue to use SFTP-based applications to upload data. The company wants to use managed services for the needs of the vendors that use legacy applications. Which solution will meet these requirements with the LEAST operational overhead?