The 403 Forbidden error when creating an Azure Cognitive Search index with REST APIs is likely due to an incorrect or missing admin API key. Make sure that you have provided the correct admin API key in Postman, as well as the other required variables such as the search service name, index name, connection string to your Azure Storage account, and container name. Double-check that you have followed the instructions in the tutorial Tutorial: Use REST and AI to generate searchable content from Azure blobs correctly, and that you have created a search service and obtained the necessary information such as the service URL and admin key.
References: