Hi Minh,
In most cases that I've seen, the marketplace owner gets a master account with a processor like PayPal or Stripe. Some processors have specific products for this. For instance, here's PayPal's solution for marketplace owners: https://www.paypal.com/us/business/platforms-and-marketplaces, and here's Stripe's product: https://stripe.com/use-cases/marketplaces
Then individual sellers/vendors need to have their own accounts where they can receive their portion of the revenue.
The marketplace owner keeps any commissions and fees that they've earned.
In essence, the fees are properly split between the website owner, and the sellers/vendors, including any shipping and sales taxes, and any credit card processing fees.
These systems are also built to handle returns/refunds and other such complex scenarios.
While it's possible for a business to manage all of this internally, it could easily add more complexity and risk to try to handle this manually.
In the Magento ecosystem, it's common to use Multi-vendor/Muilti-seller marketplace extensions that connect with a service like the ones offered by Stripe and PayPal, in order to manage all of this for the merchant. These extensions may also provide other marketplace functionality to manage things like vendor/seller product catalogs, reviews, messaging and features related to sales taxes, shipping, and other settings on a seller-by-seller basis.
Best of luck!
