You can contact firstname.lastname@example.org or fill out this contact form https://www.denodo.com/action/contact-us/ if you are doing a POV and you want help of clarification about anything related to Denodo. As you are using a Denodo free trial, someone from Denodo will reach you for giving you more details.
For connecting to the S3 you would need to use the Denodo Distributed File System Custom Wrapper. That is a DenodoConnect component that is available for download in the Dendo Support Site. For accesing this file you would need to have a valid support user.
Hope this helps!