Ok, I did some research. There is a ticket vending machine opposite Oceankaj Terminal 1. Near a kiosk, as mentioned by hallasm. The machine is outside, so it should be available also in the off-season. It's visible on Google streetview. The photo is from April 2019 though, so things could have changed since then. The bus stop is close by. See map. I think we can expect long queues, like hallasm also mentioned.