You can use client credentials (client ID/client secret) to communicate with product APIs. Login to https://auth.ui.trellix.com/ to access your Trellix IAM dashboard. See the Trellix IAM Guide and follow the instructions provided.
See the Email Security - Cloud API Reference to generate access token to use Email Cloud REST APIs.
Enable access to support user
Refer to the steps provided in the Trellix IAM Guide to enable support access.