When Accounts are on, Goodbudget can help you budget with the balance available your real life accounts, so you’ll need to select an Account to in order to save each transaction. If you’d like to just budget with just your Envelopes, you can turn Accounts off on the web in My Household: https://www.goodbudget-qa.dayspring-tech.com/household/accounts/off.
Note that you will no longer be able to import or reconcile your transactions if you’re not using the Accounts feature, nor will you be able to use Debt Accounts to track loans or credit cards you’re working to pay off.