Not knowing the specifics of your situation, I’m making a lot of assumptions here. In the steps for this guide it instructs the user to select a Billing Project when connecting to the data source (I’m assuming a BigQuery dataset). Billing needs to be “enabled” on this project that’s selected as the “Billing Project”.

Here’s a link to steps where you can confirm whether billing is enabled for this project and enable it if needed.

https://cloud.google.com/billing/docs/how-to/modify-project#...