I logged in to your site. I saw that your withdraw methods enable for paypal only. If you want to enable bank transfer then please navigate to Dokan->Settings->Selling option->Withdraw methods and set your method. Please check and let me know.
You have to manually send money to your seller by paypal. Approving withdraw request will not send money to your seller automatically. If you want to do it automatically then you have to use Paypal adaptive payment add-on for Dokan. Here is the link for this add-on- http://wedevs.com/plugin/dokan/paypal-adaptive-payments/.