Setting up an institutional account

I would like to start working in the FireCloud environment and was able to create a "personal" billing account and access the service to try it out. To establish an institutional account, I followed your instructions ("Talk to your institutional procurement office and see if they have a preferred account set-up method with Google, such as a third party reseller or an existing account.") and received a "Google Billing Account number" from the budget coordinator in our faculty. I then tried to setup a new billing account with this number (while logged to my personal account) without success. Can you provide a more detailed instructions on how to setup an institutional account and allow researchers in the faculty to use it?
Thank you!