Sounds like you might be looking at different documents. I'm not familiar with your state documents, but here are the equivalents in my area
Exclusive Right to Represent Buyer - agreement between you and your buyer's agent and broker. This is usually where you'll see a Broker/Buyer Processing Fee, as well as the overall fee (commission) that you're paying the agent/broker. This should have been disclosed to you before your agent wrote up your contract. However, it often gets added to an offer when you find the right property.
This processing fee will be added to your closing costs and listed on your settlement statement as a charge to you, the buyer.
Sales Contract with Contingencies - if the seller is contributing to your closing costs, it would be on the Financing Contingency portion of the contract (again, not sure if your state is set up the same, so the form may have a different name or be incorporated into the overall contract), there is a clear spot for "Seller Contribution" or "Seller Subsidy" or "Seller Credit". If you don't see it in the actual sales contract, it means the seller is not paying any of your closing costs.
I believe your agent/broker are referring to 3% commission they'll receive for bringing the seller a buyer (you). So "technically" the seller is paying the commission, but unless they've specifically agreed to also give you a 'contribution, subsidy, credit', than you'll be paying the processing fee.
You should get this clarified and your agent should walk you through each aspect of all the paperwork - you're absolutely right to question this fee! You can ask for it to be waived.
Here's a link to a blog my broker wrote a while back re: admin/processing fees, should give you some more insight: