At our studentlodge sites Tscharnergut, Bümpliz Nord, Bern-Bolligen und WankdorfCity there is an office desk. That is where you'll get your key. House management will show you through the house and inform you about the house rules.
On arrival out of the office hours you can get your key out of a key locker with a password.
In that case take your time for a tour of the house with house management the next day.