I need help with the Gemini API

Hello, I need help with the Gemini / Veo API.

My project is: My First Project
Project ID: project-85a5329d-d66b-4a42-b..

My billing account is active, and I have available credits on Google Cloud: R$ 1,727.36.

I have also already linked the project to billing in Google AI Studio, but the Gemini API page shows a prepaid balance of R$ 0.00.

When I try to generate video with Veo via the API, I receive this error:

429 RESOURCE_EXHAUSTED
Your prepayment credits are depleted.

The API key is linked to the My First Project project and starts with AQ.

I would like to know why my Google Cloud credits are not being applied to the Gemini/Veo API usage and how to correctly enable billing to generate videos with Veo via the API.

Thank you.