If such an auction is announced, there is always someone named to contact. If I were you, I would not take any risks and ask beforehand how it works. Because it can certainly be handled differently everywhere.
Yes, it's best to ask the auctioneer and your bank beforehand, because if you come at short notice, it may be that you will no longer receive such a confirmation in time.
Auctions carry an extremely high risk, as you usually do not have the opportunity to inspect the house for possible defects beforehand, and even any appraisals may not list all defects. What can quickly turn from a bargain into a nightmare.