Welcome to the
Kitz forum.
I plan to use the zyxel as in bridge mode only . . .
<snip>
I now have the broadband login/password I need to use the zyxel, . . .
There is a discrepancy between your two statements that I have quoted, above.
When using the ZyXEL VMG8924-B10A as a bridge / in bridge mode, it acts purely as a bridging media convertor (modem) between the protocols on the incoming metallic pathway (the telephone line) and an local internal metallic pathway (an Ethernet link) to your firewall/router/switch device, in this case your TP-Link AX1100. Once so configured in pure bridge mode, the ISP provided login/password credentials (to gain Internet access) are not entered into the ZyXEL device but are entered into the firewall/router/switch, the TP-Link device.
As
Chunkers has previously mentioned, you need to check if the AX1100 is capable of acting as a PPPoE client . . . as that is that software functionality which requires knowledge of the ISP provided login/password credentials.
[Edited to add:] Having now looked at the
relevant page on the TP-Link website, I see that the AX1100 is capable of --
WAN Types: Dynamic IP, Static IP, PPPoE, PPTP & L2TP
So you will need to configure the AX1100 as a PPPoE client which uses your ISP provided login/password credentials for Internet access.