What do you mean with "base unit"? If your Netgear provides a repeater mode, just connect it to the TP-Link's WiFi network by specifying the SSID of the WDR4300 in the Netgear's input field for the repeater to connect to. That's all. No setup necessary on the TP-Link.

However, wiring is preferable over repeater mode if possible. Since a repeater uses the same WiFi channel, repeating will reduce overall bandwidth by ~50%.

To connect one device as a pure access point (rather than a router), just put a cable between the two LANs (e.g. connect the LAN of the TP-Link with LAN of the Netgear). Make sure you disable the DHCP server on one of the devices (but not on both). Since LAN is bridged with WiFi, you get an AP this way, although it's a bit of overkill to abuse a router as a dumb AP.