User Synchronization not synchronizing

I have installed User Synchronization on both my sites - and I thought it would allow me (and others) to log into and then automatically be logged in at, but that is not happening. I still have to log in at both sites. Am I supposed to get rid of the Users I have in the sub-site (organics) before I sync the sites? I only have 3 admins right now, no other Users yet. Also, once I get this working, will it recognize paid membership levels on both sites even though I'm using Paid Memberships Pro rather than Memberships? Memberships does not do what I need it to do.