With wifi extender problems, no internet traffic, first cause is usually the (MT) DHCP server handshake failure to the client device over the wifi extender.
Got no DHCP lease IP address from the hAP ac3? Use a static address. If that works, try some DHCP workaround on the TP-Link.
I have the impression (no proof with double check tests done) that it worked in more cases with a different brand DHCP server (like my Draytek router DHCP server) for a Mikrotik AP, than when using MT DHCP, for a repeater (pseudo bridge style) setup with tp-link repeater. But MT AP-bridge with MT station-bridge always works (no pseudo-bridge here).
For what it's worth, I have in the past, connected a tplink extender and it's gotten a dhcp address from my mikrotik router and worked. However, it was connected to another tplink access point that was connected to the wired mikrotik router.