You can easily add your IBAN / bank account number to the profile yourself. Keep in mind that the IBAN you provide has to be in your own name.
This is how it works:
Press 'Hi + your name' in the top right corner of the screen.
Go to 'My profile'.
Scroll down to ‘Invoice and payment’.
Click on ‘edit’.
Fill in your bank account number and click ‘Save’.
Your bank account number has been added / changed.