Hi,
When someone buys a product, do they pay the vendor's Paypal account directly, or does the store have a Paypal account, then in turn, re-pays the commission to the vendor?
In the free version you must re-pay manually the commission to vendor. However we have a Premium version of YITH WooCommerce Multi Vendor plugin that send automatically the commission to each vendor.
For more details you can see our landing page: https://yithemes.com/themes/plugins/yith-woocommerce-multi-vendor/