Send bearer to api layer

I used the core mvc sample from github.
I’ve created an account and tried it.
I’ve put an [authorize] on the privacy endpoint of the homecontroller and it works as expected (httpcontext.user is filled with my info).

I also have a backend which I do not wish to expose publicly. So I’ve added the jwtbearer authentication and modified my okta account so the key are regenerated manually.
I used the new jwt key as issuerkey.

I wish to pass the bearer from the mvc frontend to the backend so the backend can also validate and authorize endpoints based on what is in the bearer.

How do I get the bearer from the mvc frontend ? I know how to pass it to the backend but I don’t know where it lives in the mvc frontend.

Thank you for the help.