Aside from simply facilitating P2P payments where you don't insert yourself as a middle layer, an easy way to avoid licensing is to work with a payment processor that has a digital marketplace platform solution. Stripe and Adyen have the best that I've seen.
Manage your global marketplace or platform in one place. Easily sell, get paid, and pay out as fast as you need.
www.adyen.com
Stripe Connect ist die schnellste und einfachste Möglichkeit, Zahlungen und Finanzdienstleistungen in Ihre Plattform oder Ihren Marktplatz zu integrieren.
stripe.com
They hold the money owed to the sellers by the buyers. The marketplace itself doesn't hold that money. It only withdraws its commission.
Licensing is probably not necessary in many parts of the world, for now. I believe EU was the first big mover in regulating marketplaces as financial service providers (PSD2). Their reasoning is that holding money is a financial service and there is a money laundering risk in marketplaces. E..g, you could collude with someone on a marketplace to launder money by buying something from them with stolen money. The seller gets clean money from the marketplace.