WDS is a way to enable layer-2 transparency across radio links. Because it preserves the MAC address from the traffic source, enabling WDS on bridged links is almost always recommended. WDS is not designed to interoperate between radio vendors, so using two Ubiquiti radios, users can pass virtually all traffic across wireless links.
To enable WDS, navigate to the wireless tab of the Station radio. Check the WDS box, then hit change and apply the settings. Then, do the same for the AP.
For more information, you can watch this video tutorial we've prepared.