There are two ways to add new bank credentials:

• 'Settings' > 'Add new credentials'
• Tap on the '+ Button' in the Tabbar > select 'Account'

After entering your credentials and synchronising with the bank server,  the app shows you all connected accounts with the features available for the accounts (fetching transactions and balances, making payments..).
Here you can select the accounts to show in Outbank and also rename them.