By default, all members of your organization will get a billing account created for them. This billing account will be named "First name Last Name Billing Account' which you are able to change if needed. Additionally, you can add other users to existing billing accounts should you require joint account access. For example, you may want a parent to be able to sign in on behalf of a student to pay account bills.

These billing accounts will show up under Admin > Billing & Finance > Billing > User Accounts

New accounts can be created at any time by clicking the "Create New Billing Account" button.

And the settings for each account can be modified at the top of them once opened:

If you ever need to close an account, the account balance is required to be $0.

If you prefer, you can disable the automatic creation of billing accounts in the Preferences tab under Billing Account Settings:

From that same location you can change the setting for if your organization will be absorbing the transaction fees, or if you prefer users to pay them on top of each transaction when paying online: