That direction is related to uploading additional documentation outside of what is captured within the research proposal itself. Most grant mechanisms do not allow for unlimited attachments to avoid reviewers being overwhelmed with extra documentation.
However, within the proposal itself, you have the space to discuss any preliminary (initial) data you have available. For a NSF Phase I SBIR (where it seems that you have highlighted the directions from), this is usually provided at the beginning of the Technical Discussion section. If your initial data is published, you can also reference it in relevant sections.
Hope this helps, and let us know if you have any other questions!