Authenticated with API Token and API Secret

[portsip]

Hi team,
We working on integrating the Bandwidth SMS API with our PortSIP PBX.

We have a question: at the bandwidth website(https://support.bandwidth.com/hc/en-us/articles/360033658613-How-do-I-set-up-a-Messaging-API-account-in-the-Bandwidth-App), it says use the API Token and Secret to authenticated, but in this project, I see the environment variables are using USERNAME and PASSWORD, so which one is correctly?

Thanks