TYK and Loopback 4 framework integration

I am evaluating TYK SaaS and all is fine for the moment.
I am proxiing my request to an open v3 API which is open, no autentication.

If I am deciding to use TYK Authentication mode to JWT, does this mean I have to declare my API as using JWT too ? Does this mean I have to integrate “login” methids in my API for that?

My kindest regards,