You should submit your requirements document. You should include the benefits of your system, your overall aim, your objectives and system requirements. (Ensure your objectives meet the SMART criteria, as far as possible.) This document should be detailed but it is unlikely (by this stage) to be in its full, final detail.
The detailed system requirements should be specified under headings such as: overall description, external interface requirements (user interfaces, hardware, software, communication), functional requirements, performance requirements, design constraints
In deriving your requirements you can make any assumptions you believe to be realistic. (Clearly you have no actual client to consult.) (An updated version should be included in your final report.)