Hi Mara Salem
Welcome to Microsoft Q&A Forum, thank you for posting your query here!
I'm glad that you were able to resolve your issue and thank you for posting your solution so that others experiencing the same thing can easily reference this! Since the Microsoft Q&A community has a policy that "The question author cannot accept their own answer. They can only accept answers by others ", I'll repost your solution in case you'd like to accept the answer.
Ask: Bing Visual Search API Access Denied
Solution: Your issue has been resolved. You could normally search for images and queries, but visual searches didn't work until I set the entire resource group, and not just the resource, to Bing Search.
If I missed anything please let me know and I'd be happy to add it to my answer, or feel free to comment below with any additional information.
If you have any other questions, please let me know. Thank you again for your time and patience throughout this issue.
Please don’t forget to Accept Answer and Yes for "was this answer helpful" wherever the information provided helps you, this can be beneficial to other community members.
Thank You.