What would be the correct flow?

Hi everyone, I am new to Okta and I have a question.
First let me explain my scenario, I have a mobile application (react native) and also a microservice (Gateway) created with JHipster. What I want is for my mobile app to be able to use the username and password to get an access token from okta and attach it to the headers to make a request to my service for any resource.

In Okta I created a native application using OIDC and downloaded the example for Android and ran it. This example gave me the ability to authenticate with credentials and I was able to get a token. I am attaching it in headers (Bearer $ {access_token} using postman) and only what I got is a 401 code unauthorized.

My questions are: how should I configure my service? Do I need to create a new application in okta or use the same client_id created before? Do I implement a custom web filter to validate the jwt?

I can’t understand how it works.

Thanks in advance.