Using JWT instead of Session after Login

I am willing to use Keycloak in my microservices architecture.

When I want to access a protected resource I am shown the Keycloak login form and can log in. I get redirected to the resource after login. In the request header I can see that the header Cookie: mongo-express=s%3AVpTxrBrZp_bb1kpZOuCo6nitgpTzI0YJ.6OS1ttu4hjcnut%2FG6zdyDnLk2B%2FrEmMEEw9jy2rCUrE; SESSION=510eb294-493e-4cb6-9cb8-1e09604a7fc7 is set. When I try to access the resource with an Authorization: Bearer ... header (e.g. from Postman with a previously requestet JWT) I am not able to access the resource. Instead I am shown the login form again.

How can I configure Keycloak to use JWT instead of a Session in the header after login or at least accept Authorization header with Bearer token?