The most important thing is to stand by the first set of doors on the right hand side in the direction of travel, and then exit and walk briskly. With some bad luck, there are other arrivals at the same time, though.

Wilco, did you take the test at HEL? If yes, could you check if your results were carried over to koronatietoni.fi? My assumption is that even if this is a HUS test, the results do not show up at korontatietoni.fi and you cannot print a certificate.