Dokan

If you want your users to add auctions on your WooCommerce store then you can use Dokan Lite (free plugin) to create a vendor store where your users can act as vendors and can add their own auctions. 

Requirements

• WooCommerce version 2.5.0+. You can find its documentation there only. Kindly go through it.
• Dokan Lite: Its documentation is here. Kindly go through it. 
• Ultimate Woo Auction Pro 1.0+

EXAMPLE

Let me now run through in this article an example to show how can we add users as Vendors and then how can they add an auction.

• Admin needs to allow Vendor to access their WP Back-End Panel

• Adding a Vendor

Once you have installed and activated all plugins mentioned above, then your user can register themselves as Vendors by visiting the "My Account page" which is created automatically when you activate WooCommerce. 

• Setting up Vendor Store: Once the User clicks "Register", Dokan will run through his Vendor Store settings and sets up his store.

Vendor Store will be available at: http://XYZ.com/store-list (Example URL)

• Let Vendor access WP Back-End Panel and add auction product

WP Back-end panel is available at: http://XYZ.com/wp-admin

Users can then access Products > Add New.

• Auction product is available for bidding in his store.