While your Interest Account does not have an IBAN, if you have a USD or GBP denominated Interest Account you will have an IBAN connected to a technical payments account provided to you by Vivid Money S.A. for the purposes of topping up the account via swift transfer.
If you need an Account Confirmation document for your USD or GBP Interest Account, you can do so in the app by following the steps here.
EUR denominated Interest Accounts do not currently have an IBAN nor a linked technical payments account.