Use FHIR in open EMR V7

Hi, I am trying to use FHIR in openEMR V7. I am interested in making FHIR API call to get patient health information (encounter, care plan, medications, etc…) stored in open EMR V7. my question is how to obtain JWT (Jason web token) for offline access.

I went through registration for multiple patient’s access and was authorized by data provider. I have the app client ID and secret.

Any documentation and guidance is greatly appreciated. Thanks

Zhiling