You are explaining/demoing your system to the clients or prospective users. You should assume no prior familiarity with the system on the part of the audience. Thus you should bring us quickly up to speed on the purpose and design history of the project as well as describing/illustrating it's current capabilities.
Remember to introduce yourselves, speak loudly and clearly, make eye contact all around the room, use good posture and hand position (not in pockets), etc. Quality of presentation materials/demos will count for more at this stage than they did in prior presentations. Be sure the presenting team splits the time equally.
This online material and your final written submission (item 4) will be the primary basis of the project grade, with earlier versions contributing secondarily.