The 1st April 2018 Arcada updated the self service portal AAS (Arcada Account Services). Log in to manage different aspects of your account here: https://apps.arcada.fi/aas/
Through this service you can pay the deposit for your electronic flex key. All keys registered to you and their respective deposit amount are also listed here. To get a new key, first top up your account up to the required deposit amount for the key and then pick it up at the Arcada information desk.