Jannik Hi! The transfer was probably sent as an SEPA transfer, which takes 1-2 business days?
If you didn't receive the money after 3 business days, you can contact bunq support: https://together.bunq.com/d/3218
If you go to the Home page in the bunq app, you can see all your sub-accounts. Every sub-account has its own IBAN. If you open a sub-account, its IBAN is shown at the top