I've had a similar setup some time ago. Wifi-network with an TP-Link extender as wireless adapter to wired devices.
Bridge-Mode on Meraki go doesn't stand for wifi-bridge-mode. But it is needed to make things work the way you want it to be.
You can find some information on this pages:
Meraki Go - Wireless Meshing - Cisco Meraki
Configuring VLANs in Meraki Go - Cisco Meraki
Meraki Go - Wireless Address Translation - Cisco Meraki
Meraki Go - When Bridge Mode is not Available (Auto NAT) - Cisco Meraki
Your Meraki go has to be set to "bridge mode" to allow communication between VLANs.
NAT-Mode allows Internet-access only. Devices connected to a NAT-type VLAN can't be explored.
So your guest-wifi needs to run on a NAT-type VLAN, while devices you wish to share (printer, scanner, etc) or connect to (server, NAS, etc.), need a Bridge-type VLAN.
Your TP-Link extender needs to have a static IP once connected to the Meraki Go wifi. Meraki Go - Local Network Addressing - Cisco Meraki
Make sure you picked the right VLAN for those settings.
DHCP-Server on the TP-Link needs to be turned off. This should allow devices connected to it getting the IPs assigned by Meraki Go.
When you're doing the setup, use a Laptop or PC wired to the TP-Link and keep it close to the area where one of your APs or even better your router is located. Try to reach a device connected to the wired Meraki Go VLAN before you move the repeater to it's place.