How to call get all Application Roles from Forge app

How can I call the get All Application Roles API from Forge. It does say ‘This API resource doesn’t support Oauth2 (3LO). See alternate authorization methods’, but I am bit confused about what the alternate authorization method might be.

I am trying to make a simple confluence app that shows me what users and groups have access to which product, and how many users each of those groups have.