Hi there, a common reason for getting a 404 error is if you’re not authenticated when calling the KoBo API.
According to the instructions in the Support pages Pulling Data Into Excel Power Query — KoBoToolbox documentation you need to make your data ‘public’ - however for sure if you are using JSON format (not sure about .xls format) you can definitely leave data as private and just authenticate using the normal Power BI authentication mechanisms.
This post links to a very useful UNHCR page with more detail too: KoBo - Tips & Tricks (Power BI, email notifications, listing projects etc.)
Go well!
