Hi @05065644,
Did you get a chance to review this guide? Azure Computer Vision Quickstart - Identity Client Library. It provides detailed steps for setting up authentication and using the REST API with the correct endpoint. Ensure that your endpoint matches the region of your Azure resource, and the subscription key is valid. This may help resolve the 403 and 404 errors you're facing.
Also, you can refer: Face REST API reference.
I hope this helps. Thank you.