The Political Networks 2017 Paper Archive will be hosted at SSRN and the submission system will be available after proposal acceptances have gone out. Papers will appear there typically within 24 hours after they are submitted. Note that they do hand-process papers to ensure that the metadata entered matches each paper.
Although papers are not required to be submitted, participants are strongly encouraged to do so. Note that there is an option to submit it as a private paper, so that it just appears on your author page (although it will not, of course, appear in the conference archive). You may at a later date change the visibility to public.