Credential parameter not being accepted

I am testing the RAG (TSQL) sample provided here - https://github.com/Azure-Samples/azure-sql-db-chatbot

On step 5 (05-get-search-vector.sql), the script provided is not working. What value should I put in the "Credential" parameter?

begin try
exec @retval = sp_invoke_external_rest_endpoint
@url = '/openai/deployments/embeddings/embeddings?api-version=2023-03-15-preview',
@method = 'POST',
**@credential = [https://.openai.azure.com],**
@payload = @payload,
@response = @response output;
end try