First deal assigned to end buyer, now what

[Alicia England]

I've posted before, but that deal fell through. I've gotten another deal under contract a multi-family residence (4bed 3 bath duplex) Seller agreed on a purchase price of 110k and I've assigned it to my end buyer for 120k with my assignment fee being 10k. I am so confused on what happens now. Can someone explain to me what happens between now and closing? My end buyer wants to take a look at the property and is setting up a time with the seller to do so. I feel like I made a mistake allowing the  end buyer to be in direct contact with seller but he had requested to be put in contact with seller after he signed the assignment contract. Do I do anything else on my end or do I wait until closing date and then collect my assignment fee? Thanks for your help.